Add prompt_toolkit to dependency.

[Qian-HuiChen]

For payu clone interactive mode, the PR adds prompt_toolkit >=3.0.0 to dependency. It is indirectly imported in questionary library anyway.
This aims to fix the payu deploy failure.

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.68%. Comparing base (fb8e01a) to head (6234372).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
payu/subcommands/clone_cmd.py	25.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #706   +/-   ##
=======================================
  Coverage   63.67%   63.68%           
=======================================
  Files          67       67           
  Lines        5561     5557    -4     
=======================================
- Hits         3541     3539    -2     
+ Misses       2020     2018    -2     

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[jo-basevi]

LGTM