Fix links in pull request template

[peanutfun]

Changes proposed in this PR:

• Fix broken links in pull request template

PR Author Checklist

• [x] Read the Contribution Guide
• [x] Correct target branch selected: main!
• [x] Descriptive pull request title added
• [x] Source branch up-to-date with target branch
• [ ] Documentation updated
• [ ] Tests updated
• [ ] Tests passing
• [ ] No new linter issues
• [ ] Changelog updated

PR Reviewer Checklist

• [x] Read the Contribution Guide
• [x] CLIMADA Reviewer Checklist passed
• [ ] Tests passing
• [ ] No new linter issues

[peanutfun]

Some plotting tests fail due to dependency issues. This is unrelated to the changes here.

[sarah-hlsn]

Looks good to me, tested the links, they are working, and it definitely makes sense to link to the develop branch, rather than the main branch. Merge is fine from my side, if it's no problem regarding the tests.