Fix minify step of release build by ignoring two classes

This fixes the following error during the minifyWithR8 task:

> Task :app:minifyReleaseWithR8 FAILED
ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in /home/runner/work/NewPipe/NewPipe/app/build/outputs/mapping/release/missing_rules.txt.
ERROR: R8: Missing class com.google.re2j.Matcher (referenced from: com.google.re2j.Matcher org.jsoup.helper.Re2jRegex$Re2jMatcher.delegate and 3 other contexts)
Missing class com.google.re2j.Pattern (referenced from: com.google.re2j.Pattern org.jsoup.helper.Re2jRegex.re2jPattern and 4 other contexts)

Author: TobiGr

app/proguard-rules.pro

@@ -16,6 +16,11 @@
 -dontwarn javax.script.**
 -keep class jdk.dynalink.** { *; }
 -dontwarn jdk.dynalink.**
+# Rules for jsoup
+# Ignore intended-to-be-optional re2j classes - only needed if using re2j for jsoup regex
+# jsoup safely falls back to JDK regex if re2j not on classpath, but has concrete re2j refs
+# See https://github.com/jhy/jsoup/issues/2459 - may be resolved in future, then this may be removed
+-dontwarn com.google.re2j.**
 
 ## Rules for ExoPlayer
 -keep class com.google.android.exoplayer2.** { *; }