[ISD-3791] Fix: Add timeouts for ghapi calls

[yhaliaw]

Overview

Add timeouts for all ghapi calls.
The ghapi uses urllib for making the HTTP requests to GitHub. By default there is no timeout.
This PR sets the timeout and catches the errors of urllib.

Rationale

From an investigation in the stuck process/thread in github-runner-manager, it seems it is stuck at the ghapi calls for HTTP request to GitHub.
Since the HTTP request by ghapi with urllib has no timeout, this is the most likely reason for the stuck process/thread.

EDIT: This is likely not the reason for the stuck process/thread. However, setting timeouts is generally a good practice.

Checklist

• The charm style guide was applied.
• The contributing guide was applied.
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex).
• The changelog is updated with changes that affects the users of the charm.

[github-actions]

Test results for commit a401192

Test coverage for a401192

Wrote XML report to coverage/coverage.xml

Static code analysis report

Run started:2025-07-10 06:40:37.580658

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 2055
  Total lines skipped (#nosec): 2
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 1

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):