fission-src/.github/PULL_REQUEST_TEMPLATE.md

Description

Which issue(s) this PR fixes:

Fixes #

Testing

Checklist:

• I ran tests as well as code linting locally to verify my changes.
• I have done manual verification of my changes, changes working as expected.
• I have added new tests to cover my changes.
• My changes follow contributing guidelines of Fission.
• I have signed all of my commits.