screenshotTest: uninstall app before running

Signed-off-by: Álvaro Brey Vilas <alvaro.brey@nextcloud.com>

.github/workflows/screenShotTest.yml

@@ -71,7 +71,7 @@ jobs:
                     sdcard-path-or-size: 100M
                     target: google_apis
                     emulator-options: -no-window -gpu swiftshader_indirect -no-snapshot -noaudio -no-boot-anim -skin 500x833
-                    script: ./gradlew gplayDebugExecuteScreenshotTests -Pandroid.testInstrumentationRunnerArguments.annotation=com.owncloud.android.utils.ScreenshotTest -Pandroid.testInstrumentationRunnerArguments.COLOR=${{ matrix.color }} -Pandroid.testInstrumentationRunnerArguments.DARKMODE=${{ matrix.scheme }}
+                    script: ./gradlew uninstallAll gplayDebugExecuteScreenshotTests -Pandroid.testInstrumentationRunnerArguments.annotation=com.owncloud.android.utils.ScreenshotTest -Pandroid.testInstrumentationRunnerArguments.COLOR=${{ matrix.color }} -Pandroid.testInstrumentationRunnerArguments.DARKMODE=${{ matrix.scheme }}
             -   name: upload failing results
                 if: ${{ failure() }}
                 run: