Bump checkstyle and make inner classes final

Updating checkstyle fixed a vulnerability and fixed a final class check in version 10.12.2 for local classes without constructor.  Local classes without a constructor should be marked as final. That is done in this commit.

For more info see https://github.com/checkstyle/checkstyle/releases/tag/checkstyle-10.12.2

Author: TobiGr

app/src/main/java/org/schabi/newpipe/fragments/list/search/SuggestionListAdapter.java

@@ -76,7 +76,8 @@ private void updateFrom(final SuggestionItem item) {
         }
     }
 
-    private static class SuggestionItemCallback extends DiffUtil.ItemCallback<SuggestionItem> {
+    private static final class SuggestionItemCallback
+            extends DiffUtil.ItemCallback<SuggestionItem> {
         @Override
         public boolean areItemsTheSame(@NonNull final SuggestionItem oldItem,
                                        @NonNull final SuggestionItem newItem) {

app/src/main/java/org/schabi/newpipe/settings/PeertubeInstanceListFragment.java

@@ -396,7 +396,8 @@ void bind(final int position) {
         }
     }
 
-    private static class PeertubeInstanceCallback extends DiffUtil.ItemCallback<PeertubeInstance> {
+    private static final class PeertubeInstanceCallback
+            extends DiffUtil.ItemCallback<PeertubeInstance> {
         @Override
         public boolean areItemsTheSame(@NonNull final PeertubeInstance oldItem,
                                        @NonNull final PeertubeInstance newItem) {

app/src/main/java/org/schabi/newpipe/settings/SelectChannelFragment.java

@@ -174,7 +174,7 @@ public interface OnCancelListener {
         void onCancel();
     }
 
-    private class SelectChannelAdapter
+    private final class SelectChannelAdapter
             extends RecyclerView.Adapter<SelectChannelAdapter.SelectChannelItemHolder> {
         @NonNull
         @Override

app/src/main/java/org/schabi/newpipe/settings/SelectFeedGroupFragment.java

@@ -175,7 +175,7 @@ public interface OnCancelListener {
         void onCancel();
     }
 
-    private class SelectFeedGroupAdapter
+    private final class SelectFeedGroupAdapter
             extends RecyclerView.Adapter<SelectFeedGroupAdapter.SelectFeedGroupItemHolder> {
         @NonNull
         @Override

app/src/main/java/org/schabi/newpipe/settings/SelectPlaylistFragment.java

@@ -138,7 +138,7 @@ public interface OnSelectedListener {
         void onRemotePlaylistSelected(int serviceId, String url, String name);
     }
 
-    private class SelectPlaylistAdapter
+    private final class SelectPlaylistAdapter
             extends RecyclerView.Adapter<SelectPlaylistAdapter.SelectPlaylistItemHolder> {
         @NonNull
         @Override

app/src/main/java/org/schabi/newpipe/settings/preferencesearch/PreferenceSearchAdapter.java

@@ -69,7 +69,8 @@ static class PreferenceViewHolder extends RecyclerView.ViewHolder {
         }
     }
 
-    private static class PreferenceCallback extends DiffUtil.ItemCallback<PreferenceSearchItem> {
+    private static final class PreferenceCallback
+            extends DiffUtil.ItemCallback<PreferenceSearchItem> {
         @Override
         public boolean areItemsTheSame(@NonNull final PreferenceSearchItem oldItem,
                                        @NonNull final PreferenceSearchItem newItem) {

gradle/libs.versions.toml

@@ -11,7 +11,7 @@ assertj = "3.24.2"
 autoservice = "1.1.1"
 bridge = "v2.0.2"
 cardview = "1.0.0"
-checkstyle = "10.12.1"
+checkstyle = "10.26.1"
 constraintlayout = "2.1.4"
 core = "1.12.0"
 desugar = "2.0.4"