Fix widget bookmarks always going to last page

[ahmedre]

Widgets need to have the mutable flag since the pending intent template
needs to be mutated per row.

[github-actions]

OLD: app-madani-debug.apk (signature: V1, V2)
NEW: app-madani-debug.apk (signature: V1, V2)

          │          compressed          │         uncompressed         
          ├───────────┬───────────┬──────┼───────────┬───────────┬──────
 APK      │ old       │ new       │ diff │ old       │ new       │ diff 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
      dex │  11.8 MiB │  11.8 MiB │ +2 B │    30 MiB │    30 MiB │  0 B 
     arsc │   1.9 MiB │   1.9 MiB │  0 B │   1.9 MiB │   1.9 MiB │  0 B 
 manifest │   5.8 KiB │   5.8 KiB │  0 B │  28.6 KiB │  28.6 KiB │  0 B 
      res │   1.6 MiB │   1.6 MiB │  0 B │   1.8 MiB │   1.8 MiB │  0 B 
    asset │ 404.2 KiB │ 404.2 KiB │  0 B │ 678.6 KiB │ 678.6 KiB │  0 B 
    other │   181 KiB │   181 KiB │ +4 B │   365 KiB │   365 KiB │  0 B 
──────────┼───────────┼───────────┼──────┼───────────┼───────────┼──────
    total │  15.9 MiB │  15.9 MiB │ +6 B │  34.7 MiB │  34.7 MiB │  0 B