Update gradle, kotlin and other dependencies (#2291)

* update gradle, kotlin and other dependencies

* fix new warnings

* remove unused import

* update Proguard rules

* add explicit dependency on Gson to get the newest version

* remove debug flag from proguard rules again

* fix typo

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationsFragment.kt

@@ -52,6 +52,7 @@ import kotlinx.coroutines.launch
 import java.io.IOException
 import javax.inject.Inject
 
+@OptIn(ExperimentalPagingApi::class)
 class ConversationsFragment : SFragment(), StatusActionListener, Injectable, ReselectableFragment {
 
     @Inject
@@ -72,7 +73,6 @@ class ConversationsFragment : SFragment(), StatusActionListener, Injectable, Res
         return inflater.inflate(R.layout.fragment_timeline, container, false)
     }
 
-    @ExperimentalPagingApi
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         val preferences = PreferenceManager.getDefaultSharedPreferences(view.context)
 

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationsRemoteMediator.kt

@@ -7,7 +7,7 @@ import androidx.paging.RemoteMediator
 import com.keylesspalace.tusky.db.AppDatabase
 import com.keylesspalace.tusky.network.MastodonApi
 
-@ExperimentalPagingApi
+@OptIn(ExperimentalPagingApi::class)
 class ConversationsRemoteMediator(
     private val accountId: Long,
     private val api: MastodonApi,

app/src/main/java/com/keylesspalace/tusky/components/conversation/ConversationsViewModel.kt

@@ -37,7 +37,7 @@ class ConversationsViewModel @Inject constructor(
     private val api: MastodonApi
 ) : RxAwareViewModel() {
 
-    @ExperimentalPagingApi
+    @OptIn(ExperimentalPagingApi::class)
     val conversationFlow = Pager(
         config = PagingConfig(pageSize = 10, enablePlaceholders = false, initialLoadSize = 20),
         remoteMediator = ConversationsRemoteMediator(accountManager.activeAccount!!.id, api, database),