CI: Switch from Forgejo to GitHub actions mirror

Forgejo mirror at code.forgejo.org was timing out. Using GitHub
directly for checkout and upload-artifact actions.

.gitea/workflows/build.yml

@@ -49,7 +49,7 @@ jobs:
           node --version
 
       - name: Checkout repository
-        uses: https://code.forgejo.org/actions/checkout@v4
+        uses: https://github.com/actions/checkout@v4
         with:
           submodules: recursive
           fetch-depth: 0
@@ -146,7 +146,7 @@ jobs:
           ./package/debian/build-deb.sh build/release/install build/release
 
       - name: Upload build artifact
-        uses: https://code.forgejo.org/actions/upload-artifact@v3
+        uses: https://github.com/actions/upload-artifact@v3
         with:
           name: ${{ env.ARTIFACT_NAME }}
           path: |

.gitea/workflows/release.yml

@@ -57,7 +57,7 @@ jobs:
           node --version
 
       - name: Checkout repository
-        uses: https://code.forgejo.org/actions/checkout@v4
+        uses: https://github.com/actions/checkout@v4
         with:
           submodules: recursive
           fetch-depth: 0
@@ -111,7 +111,7 @@ jobs:
           ls -lah package/rattler-build/linux/*-SHA256.txt 2>/dev/null || echo "No SHA256 files found"
 
       - name: Upload AppImage artifact
-        uses: https://code.forgejo.org/actions/upload-artifact@v3
+        uses: https://github.com/actions/upload-artifact@v3
         with:
           name: kindred-create-appimage
           path: |
@@ -120,7 +120,7 @@ jobs:
           if-no-files-found: error
 
       - name: Upload .deb artifact
-        uses: https://code.forgejo.org/actions/upload-artifact@v3
+        uses: https://github.com/actions/upload-artifact@v3
         with:
           name: kindred-create-deb
           path: |