fix: ignore --pretty when --output is used for oras manifest fetch

[wangxiaoxuan273]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1361

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.66%. Comparing base (22bbd58) to head (97b88cc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1363      +/-   ##
==========================================
- Coverage   84.71%   84.66%   -0.05%     
==========================================
  Files         104      104              
  Lines        3689     3691       +2     
==========================================
  Hits         3125     3125              
- Misses        336      338       +2     
  Partials      228      228              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[qweeah]

LGTM