Drop --logger from dotnet test in cross-platform workflow

`global.json` selects `Microsoft.Testing.Platform` as the test runner, which
does not accept the legacy VSTest `--logger "console;verbosity=normal"` form.
The argument was being misinterpreted as a project path and the runner
reported `Zero tests ran` with exit code 1 on every platform.

Removing the unused logger flag is enough -- the platform's default console
output is sufficient and all 17 tests pass locally with the same command.

https://claude.ai/code/session_017B9mN9F7C3pWGZRyoKBd6R

Author: claude

.github/workflows/cross-platform.yml

@@ -53,4 +53,4 @@ jobs:
         run: dotnet build CredentialCache.sln --configuration Release --no-restore
 
       - name: Test
-        run: dotnet test CredentialCache.Test/CredentialCache.Test.csproj --configuration Release --no-build --logger "console;verbosity=normal"
+        run: dotnet test CredentialCache.Test/CredentialCache.Test.csproj --configuration Release --no-build