completions: fix some issues with zsh completions

[jdx]

Fixes #1079

[codecov]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (95c78ed) 86.36% compared to head (96edced) 83.68%.

Files	Patch %	Lines
src/cli/render_completion.rs	95.06%	8 Missing ⚠️
src/cli/plugins/uninstall.rs	62.50%	3 Missing ⚠️
src/cli/alias/ls.rs	80.00%	1 Missing ⚠️
src/cli/plugins/ls.rs	50.00%	1 Missing ⚠️
src/cli/plugins/mod.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1080      +/-   ##
==========================================
- Coverage   86.36%   83.68%   -2.69%     
==========================================
  Files         134      134              
  Lines       12589    12675      +86     
==========================================
- Hits        10873    10607     -266     
- Misses       1716     2068     +352     

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