Don't set kapt stub gen task to 1.9

[ahmedre]

It doesn't seem to be necessary.

[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 │  20.4 MiB │  20.4 MiB │ +200 B │  65.8 MiB │  65.8 MiB │ +324 B 
     arsc │   2.3 MiB │   2.3 MiB │    0 B │   2.3 MiB │   2.3 MiB │    0 B 
 manifest │   5.6 KiB │   5.6 KiB │    0 B │  27.1 KiB │  27.1 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 │ 189.2 KiB │ 189.2 KiB │   +3 B │ 386.8 KiB │ 386.8 KiB │    0 B 
──────────┼───────────┼───────────┼────────┼───────────┼───────────┼────────
    total │  24.8 MiB │  24.8 MiB │ +203 B │  70.9 MiB │  70.9 MiB │ +324 B