Bump sanic from 21.9.3 to 21.12.2 in /build

Bumps [sanic](https://github.com/sanic-org/sanic) from 21.9.3 to 21.12.2.
- [Release notes](https://github.com/sanic-org/sanic/releases)
- [Changelog](https://github.com/sanic-org/sanic/blob/main/CHANGELOG.rst)
- [Commits](sanic-org/sanic@v21.9.3...v21.12.2)

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

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

Author: dependabot[bot]

build/requirements.txt

@@ -1,6 +1,6 @@
 wheel
 pygame==2.0.2
-sanic==21.9.3
+sanic==21.12.2
 sanic-Cors==2.0.1
 syncer==1.3.0
 aiohttp==3.7.4