Lint: make missing plural quantity a warning as they have to be properly translated.
Occurred when upgrading to Android Gradle plugin 7.1.0.
<issue id="ExtraTranslation" severity="error" />
<issue id="GifUsage" severity="error" />
<issue id="InconsistentArrays" severity="error" />
+ <issue id="MissingQuantity"
+ severity="warning" />
<issue id="MissingTranslation" severity="warning" />
<issue id="Proguard" severity="warning" />
<issue id="ScrollViewCount" severity="error" />
