ci: update actions to latest major versions

Update GitHub Actions in release and watch workflows:
- Bump actions/checkout from v4 to v6 for improved performance and
  security.
- Bump actions/upload-artifact from v4 to v7 for latest features and
  fixes.

This ensures workflows use the most up-to-date and supported actions.

Author: johanvx

.github/workflows/release.yml

@@ -10,7 +10,7 @@ jobs:
       contents: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           fetch-tags: true
@@ -23,7 +23,7 @@ jobs:
       - name: Build PDF with PDF/UA-1
         run: typst compile --pdf-standard ua-1 undergradmath.typ
       - name: Upload PDF as artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: Undergradmath
           path: undergradmath.pdf

.github/workflows/watch.yml

@@ -11,7 +11,7 @@ jobs:
       modified: ${{ contains(steps.changed-files.outputs.modified_files, 'undergradmath.typ') }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Check changed files
         id: changed-files
         uses: tj-actions/changed-files@v46
@@ -24,7 +24,7 @@ jobs:
     if: needs.check-changed.outputs.modified == 'true'
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
       - name: Update Homebrew
         run: brew update
       - name: Install Typst
@@ -34,7 +34,7 @@ jobs:
       - name: Build PDF with PDF/UA-1
         run: typst compile --pdf-standard ua-1 undergradmath.typ
       - name: Upload PDF as artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: Undergradmath
           path: undergradmath.pdf