fix: add flow_type to client options

[silentworks]

What kind of change does this PR introduce?

Add flow_type option to client options for gotrue-py

What is the current behavior?

Only supports implicit auth flow

What is the new behavior?

Can now select between pkce and implicit auth flow

Additional context

Add any other context or screenshots.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ca79bbd) 69.54% compared to head (f1d8cba) 70.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #610      +/-   ##
==========================================
+ Coverage   69.54%   70.00%   +0.45%     
==========================================
  Files           9        9              
  Lines         197      200       +3     
==========================================
+ Hits          137      140       +3     
  Misses         60       60              

Files	Coverage Δ
supabase/client.py	68.42% <ø> (ø)
supabase/lib/auth_client.py	81.81% <100.00%> (ø)
supabase/lib/client_options.py	100.00% <100.00%> (ø)

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[anand2312]

LGTM