Replace deprecated set-output with $GITHUB_OUTPUT in Deploy workflow (#412)

GitHub deprecated the `::set-output` workflow command in October 2022,
with support fully removed. The `Deploy.yml` workflow still used the old
syntax.

## Changes

- **`.github/workflows/Deploy.yml`**: Replace `::set-output` with the
`$GITHUB_OUTPUT` environment file approach (PowerShell syntax,
consistent with `shell: pwsh` default):

```diff
- echo "::set-output name=TAG_VERSION::$tagVersion"
+ echo "TAG_VERSION=$tagVersion" >> $env:GITHUB_OUTPUT
```

<!-- START COPILOT CODING AGENT TIPS -->
---

✨ Let Copilot coding agent [set things up for
you](https://github.com/IntelliTect/CodingGuidelines/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot)
— coding agent works faster and does higher quality work when set up for
your repo.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: BenjaminMichaelis <22186029+BenjaminMichaelis@users.noreply.github.com>

Author: Copilot

.github/workflows/Deploy.yml

@@ -60,6 +60,6 @@ jobs:
       - name: Push NuGet
         run: |
           $tagVersion = "${{ github.ref }}".substring(11)
-          echo "::set-output name=TAG_VERSION::$tagVersion"
+          echo "TAG_VERSION=$tagVersion" >> $env:GITHUB_OUTPUT
           dotnet nuget push IntelliTect.Analyzers.$tagVersion.nupkg --source https://api.nuget.org/v3/index.json --api-key ${{ secrets.NUGET_API_KEY }} --skip-duplicate
         id: tag-version

Directory.Packages.props

@@ -1,25 +1,25 @@
-<Project>
-  <PropertyGroup>
-    <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
-    <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
-  </PropertyGroup>
-  <ItemGroup>
-    <PackageVersion Include="coverlet.collector" Version="8.0.0" />
-    <PackageVersion Include="IntelliTect.Analyzers" Version="0.2.0" />
-    <PackageVersion Include="Microsoft.Build.Framework" Version="18.4.0" />
-    <PackageVersion Include="Microsoft.Build.Locator" Version="1.11.2" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="5.3.0" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="5.3.0" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="10.0.201" />
-    <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="5.3.0" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
-    <PackageVersion Include="MSTest.TestAdapter" Version="4.1.0" />
-    <PackageVersion Include="MSTest.TestFramework" Version="4.1.0" />
-    <PackageVersion Include="System.CommandLine.DragonFruit" Version="0.4.0-alpha.25320.106" />
-    <!-- Reference-only packages for test framework namespace resolution in analyzer tests -->
-    <PackageVersion Include="xunit.v3.core" Version="3.2.2" />
-    <PackageVersion Include="NUnit" Version="4.5.1" />
-    <PackageVersion Include="TUnit.Core" Version="1.19.57" />
-  </ItemGroup>
-</Project>
+<Project>
+  <PropertyGroup>
+    <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
+    <CentralPackageTransitivePinningEnabled>false</CentralPackageTransitivePinningEnabled>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageVersion Include="coverlet.collector" Version="8.0.0" />
+    <PackageVersion Include="IntelliTect.Analyzers" Version="0.2.0" />
+    <PackageVersion Include="Microsoft.Build.Framework" Version="18.4.0" />
+    <PackageVersion Include="Microsoft.Build.Locator" Version="1.11.2" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="5.3.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="5.3.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="10.0.201" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="5.3.0" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
+    <PackageVersion Include="MSTest.TestAdapter" Version="4.1.0" />
+    <PackageVersion Include="MSTest.TestFramework" Version="4.1.0" />
+    <PackageVersion Include="System.CommandLine.DragonFruit" Version="0.4.0-alpha.25320.106" />
+    <!-- Reference-only packages for test framework namespace resolution in analyzer tests -->
+    <PackageVersion Include="xunit.v3.core" Version="3.2.2" />
+    <PackageVersion Include="NUnit" Version="4.5.1" />
+    <PackageVersion Include="TUnit.Core" Version="1.19.57" />
+  </ItemGroup>
+</Project>