fix(preview-text-fragment): finish

[alperozturk96]

Issue

Exception java.lang.IllegalStateException:
  at androidx.fragment.app.Fragment.requireActivity (Fragment.java:1005)
  at com.owncloud.android.ui.preview.PreviewTextFragment.finish$lambda$0 (PreviewTextFragment.kt:169)
  at com.owncloud.android.ui.preview.PreviewTextFragment$$ExternalSyntheticLambda0.run (D8$$SyntheticClass)
  at android.os.Handler.handleCallback (Handler.java:1070)
  at android.os.Handler.dispatchMessage (Handler.java:125)
  at android.os.Looper.dispatchMessage (Looper.java:358)
  at android.os.Looper.loopOnce (Looper.java:288)
  at android.os.Looper.loop (Looper.java:392)
  at android.app.ActivityThread.main (ActivityThread.java:10346)
  at java.lang.reflect.Method.invoke
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:638)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:972)

[github-actions]

blue-Light-Screenshot test failed, but no output was generated. Maybe a preliminary stage failed.

[github-actions]

Codacy

SpotBugs

Category	Base	New
Bad practice	32	32
Correctness	66	66
Dodgy code	213	213
Experimental	1	1
Malicious code vulnerability	2	2
Multithreaded correctness	29	29
Performance	41	41
Security	19	19
Total	403	403

[github-actions]

master-IT test failed: https://www.kaminsky.me/nc-dev/android-integrationTests/17322-IT-master-16-14