docs: only lists are accepted when specifying objects to prune

[alexander-held]

Description

Resolves #1684.

As confirmed by @kratsg, the pruning API was meant to take lists to specify which modifiers / samples etc. are meant to be pruned, and to not support strings in addition to that. This updates the docstrings in the public and internal API to reflect the implementation: as shown in the example in #1684, only lists are supported.

Checklist Before Requesting Reviewer

• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

Before Merging

For the PR Assignees:

• Summarize commit messages into a comprehensive review of the PR

* Correct Workspace.prune docstrings to indicate lists are accepted

[codecov]

Codecov Report

Merging #1692 (e176353) into master (39a9e92) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1692   +/-   ##
=======================================
  Coverage   98.05%   98.05%           
=======================================
  Files          64       64           
  Lines        4220     4220           
  Branches      587      587           
=======================================
  Hits         4138     4138           
  Misses         49       49           
  Partials       33       33           

Flag	Coverage Δ
contrib	25.35% <ø> (ø)
doctest	61.13% <ø> (ø)
unittests	96.37% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pyhf/workspace.py	100.00% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 39a9e92...e176353. Read the comment docs.

[matthewfeickert]

LGTM. 👍 Thanks @alexander-held!