build(deps): bump mysql from 6a5dbd2 to c0455ac in /examples/mysql (

envoyproxy#28967)

Bumps mysql from `6a5dbd2` to `c0455ac`.

---
updated-dependencies:
- dependency-name: mysql
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

examples/mysql/Dockerfile-mysql

@@ -1 +1 @@
-FROM mysql:8.1.0@sha256:6a5dbd2819e36048669639811461f27fee48da1e22039e5d31f4273a20d542f6
+FROM mysql:8.1.0@sha256:c0455ac041844b5e65cd08571387fa5b50ab2a6179557fd938298cab13acf0dd