chore(deps): Update Android Gradle Plugin to v8.5.1

They told me on 8th of July that AGP up to v8.6-alpha will be supported
on next IDEA (for EAP, because of it is... at this point I think
Ultimate Edition no longer worth it, at least for KMM developers) plugin
release, let's see if they're telling the truth.

CHANGELOG.md

@@ -47,4 +47,5 @@
 - Use version catalog for gradle plugins
 - Update dependency org.jsoup:jsoup to v1.7.1
 - Bump dependency com.github.tachiyomiorg:image-decoder revision to 41c059e540
-- Bump dependency io.coil-kt.coil3 to v3.0.0-alpha08
+- Update dependency io.coil-kt.coil3 to v3.0.0-alpha08
+- Update Android Gradle Plugin to v8.5.1

gradle/androidx.versions.toml

@@ -1,6 +1,6 @@
 [versions]
 activity = "1.9.0"
-agp = "8.4.2"
+agp = "8.5.1"
 lifecycle = "2.8.1"
 
 [libraries]

settings.gradle.kts

@@ -11,16 +11,6 @@ pluginManagement {
             }
         }
     }
-    // https://issuetracker.google.com/344363457
-    // FIXME: Remove when AGP's bundled R8 is updated
-    buildscript {
-        repositories {
-            maven("https://storage.googleapis.com/r8-releases/raw")
-        }
-        dependencies {
-            classpath("com.android.tools:r8:8.5.21")
-        }
-    }
 }
 
 dependencyResolutionManagement {