GitHub workflow: Run harmless gradlew command due to warnings

We have a workflow job which runs:

./gradlew -q printLineCoverage

which should ONLY print out a number (e.g. 99.7)

but unfortunately the Android plugin spams a bunch of noise on
first run that we don't care about (that's why we pass in the
`-q` option). This is causing the
"COVERAGE=(./gradlew -q printLineCoverage)>>GITHUB_ENV" action
to fail.

The output looks like:

```
Warning: Errors during XML parse:
Warning: Additionally, the fallback loader failed to parse the XML.
Checking the license for package Android SDK Platform-Tools in /usr/local/lib/android/sdk/licenses
License for package Android SDK Platform-Tools accepted.
Preparing "Install Android SDK Platform-Tools v.35.0.2".
"Install Android SDK Platform-Tools v.35.0.2" ready.
Installing Android SDK Platform-Tools in /usr/local/lib/android/sdk/platform-tools
"Install Android SDK Platform-Tools v.35.0.2" complete.
"Install Android SDK Platform-Tools v.35.0.2" finished.
99.7
```

By running a harmless Gradle command first, we clear this initial
noise out of the way so that printLineCoverage can run cleanly.

Author: bitspittle

.github/workflows/coverage-badge.yml

@@ -28,6 +28,14 @@ jobs:
           path: ~/.konan
           key: kotlin-native-compiler-${{ runner.OS }}
 
+      # At some point, the Android plugin started getting chatty with its output
+      # and spams stuff like "Install Android SDK ..."
+      # This will mess up the next command (gradlw -q printLineCoverage) so we just
+      # run a harmless task first.
+      - name: Run Gradle once to clear Android startup messages
+        run: |
+          ${{github.workspace}}/gradlew tasks
+
       - name: Generate coverage output
         run: |
           echo "COVERAGE=$(${{github.workspace}}/gradlew -q printLineCoverage)" >> $GITHUB_ENV