fix(ci): make tests need builds to complete

The wait for action is not reliable, so tests are running before builds
have completed. By adding the explicit needs, tests will run at the
right time, but it will make workflow runs a bit slower.

.github/workflows/main.yml

@@ -235,6 +235,7 @@ jobs:
 
   test:
     name: Test (${{ matrix.platform }}, ${{ matrix.arch }}, ${{ matrix.godot-version }})
+    needs: [build-linux, build-other-platforms]
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false