fix(deps): Downgrade file_picker to 8.1.4 to fix Android build errors

[provokateurin]

It got bumped in #2712 which triggered miguelpruivo/flutter_file_picker#1643 so we have to downgrade it for now.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.90%. Comparing base (f9a1b06) to head (e995688).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2713   +/-   ##
=======================================
  Coverage   28.90%   28.90%           
=======================================
  Files         373      373           
  Lines      136645   136645           
=======================================
  Hits        39497    39497           
  Misses      97148    97148           

Flag	Coverage Δ		*Carryforward flag
account_repository	98.47% <ø> (ø)
cookie_store	99.48% <ø> (ø)		Carriedforward from f9a1b06
dashboard_app	96.05% <ø> (ø)
dynamite	31.05% <ø> (ø)		Carriedforward from f9a1b06
dynamite_end_to_end_test	61.69% <ø> (ø)		Carriedforward from f9a1b06
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from f9a1b06
interceptor_http_client	97.18% <ø> (ø)		Carriedforward from f9a1b06
neon_dashboard	96.05% <ø> (ø)		Carriedforward from f9a1b06
neon_framework	59.34% <ø> (ø)
neon_http_client	93.61% <ø> (ø)		Carriedforward from f9a1b06
neon_notifications	100.00% <ø> (ø)		Carriedforward from f9a1b06
neon_rich_text	100.00% <ø> (ø)
neon_storage	94.66% <ø> (ø)		Carriedforward from f9a1b06
neon_talk	99.45% <ø> (ø)		Carriedforward from f9a1b06
nextcloud	24.33% <ø> (ø)		Carriedforward from f9a1b06
notifications_app	97.36% <ø> (ø)
notifications_push_repository	98.11% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from f9a1b06
talk_app	98.83% <ø> (ø)

*This pull request uses carry forward flags. Click here to find out more.