Bump sanic from 20.12.6 to 20.12.7 in /tests/requirements (#1606)

Bumps [sanic](https://github.com/sanic-org/sanic) from 20.12.6 to 20.12.7.
- [Release notes](https://github.com/sanic-org/sanic/releases)
- [Changelog](https://github.com/sanic-org/sanic/blob/main/CHANGELOG.rst)
- [Commits](sanic-org/sanic@v20.12.6...v20.12.7)

---
updated-dependencies:
- dependency-name: sanic
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

tests/requirements/reqs-sanic-20.12.txt

@@ -1,2 +1,2 @@
-sanic==20.12.6
+sanic==20.12.7
 -r reqs-base.txt