build(deps): Bump gaplint from 1.1.5 to 1.2.1

Bumps [gaplint](https://github.com/james-d-mitchell/gaplint) from 1.1.5 to 1.2.1.
- [Release notes](https://github.com/james-d-mitchell/gaplint/releases)
- [Commits](james-d-mitchell/gaplint@v1.1.5...v1.2.1)

---
updated-dependencies:
- dependency-name: gaplint
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1 +1 @@
-gaplint==1.1.5
+gaplint==1.2.1