Bump com.uber.nullaway:nullaway from 0.10.19 to 0.10.21

Bumps [com.uber.nullaway:nullaway](https://github.com/uber/NullAway) from 0.10.19 to 0.10.21.
- [Release notes](https://github.com/uber/NullAway/releases)
- [Changelog](https://github.com/uber/NullAway/blob/master/CHANGELOG.md)
- [Commits](uber/NullAway@v0.10.19...v0.10.21)

---
updated-dependencies:
- dependency-name: com.uber.nullaway:nullaway
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

gradle/libs.versions.toml

@@ -18,7 +18,7 @@ ipaddress = { module = "com.github.seancfoley:ipaddress", version.ref = "ipaddre
 jakarta-mail-api = { module = "jakarta.mail:jakarta.mail-api", version = "2.1.2" }
 junit-bom = { module = "org.junit:junit-bom", version.ref = "junit" }
 maven-plugin = { module = "com.vanniktech:gradle-maven-publish-plugin", version.ref = "maven-publish" }
-nullaway = { module = "com.uber.nullaway:nullaway", version = "0.10.19" }
+nullaway = { module = "com.uber.nullaway:nullaway", version = "0.10.21" }
 protobuf-java = { module = "com.google.protobuf:protobuf-java", version.ref = "protobuf" }
 spotless = { module = "com.diffplug.spotless:spotless-plugin-gradle", version = "6.23.3" }