fix(install): install older ComfyUI versions by tag

[Xyc2016]

Fixes issue with installing older ComfyUI versions.

The GitHub Releases API defaults to 30 releases per page, so older versions may not be visible when fetching releases. While it is possible to fetch additional pages, this PR simplifies the workflow by directly checking out the requested git tag, allowing installation of any stable release version without relying on release pagination.

References: #340

[codecov]

Codecov Report

❌ Patch coverage is 0% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
comfy_cli/command/install.py	0.00%	7 Missing ⚠️

@@            Coverage Diff             @@
##             main     #350      +/-   ##
==========================================
- Coverage   52.23%   51.93%   -0.30%     
==========================================
  Files          32       32              
  Lines        3519     3489      -30     
==========================================
- Hits         1838     1812      -26     
+ Misses       1681     1677       -4     

Files with missing lines	Coverage Δ
comfy_cli/command/install.py	55.11% <0.00%> (-2.06%)	⬇️

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[bigcat88]

Can you remove the fetch_github_releases , parse_releases and select_version functions if they are not used anymore?

[Xyc2016]

@bigcat88
I’ve removed fetch_github_releases, parse_releases, and select_version along with their associated tests since they’re no longer used after switching to tag-based checkout.

[bigcat88]

Thanks for this PR!