CI: Differentiate Linux CI artifact names

Use the entries in the matrix.ubuntu property to differentiate the
Linux CI artifacts. This allows us to have separate artifacts for each
job configuration created by the matrix.

.github/workflows/main.yml

@@ -266,7 +266,7 @@ jobs:
         if: ${{ success() && (github.event_name != 'pull_request' || env.SEEKING_TESTERS == '1') }}
         uses: actions/upload-artifact@v3
         with:
-          name: 'obs-linux-deb'
+          name: 'obs-linux-${{ matrix.ubuntu }}-deb'
           path: '${{ github.workspace }}/obs-studio/build/${{ env.FILE_NAME }}'
 
   windows_build: