Maintenance updates: Use Actions, start changelog, auto-upload to pypi

[The below is a manually-edited version of the text created upon clicking the "Auto-generate release notes" button.]

What's Changed

• Replace Travis CI with GitHub Actions by @hakonanes in #13
• Add changelog and other minor documentation changes by @hakonanes in #16
• Automatically upload source dist to PyPI on tagged GitHub release by @hakonanes in #17
• Remove setup_requires from setup.py by @hakonanes in #18

New Contributors

• @hakonanes made their first contribution in #13

Full Changelog: https://github.com/vaipatel/morphops/commits/v0.1.13 [This includes all changes since init because it's the first tagged release]