Bump nimbus-jose-jwt from 9.19 to 9.21 (#743)

Bumps [nimbus-jose-jwt](https://bitbucket.org/connect2id/nimbus-jose-jwt) from 9.19 to 9.21.
- [Changelog](https://bitbucket.org/connect2id/nimbus-jose-jwt/src/master/CHANGELOG.txt)
- [Commits](https://bitbucket.org/connect2id/nimbus-jose-jwt/branches/compare/9.21..9.19)

---
updated-dependencies:
- dependency-name: com.nimbusds:nimbus-jose-jwt
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

Author: dependabot[bot]

line-bot-api-client/build.gradle

@@ -57,7 +57,7 @@ dependencies {
     integrationTestImplementation 'io.jsonwebtoken:jjwt-jackson'
     // https://github.com/jwtk/jjwt/issues/236 jjwt doens't support JWK parsing, yet.
     // Once jjwt support JWK, we can remove this dependency.
-    integrationTestImplementation 'com.nimbusds:nimbus-jose-jwt:9.19'
+    integrationTestImplementation 'com.nimbusds:nimbus-jose-jwt:9.21'
     integrationTestImplementation 'org.springframework.boot:spring-boot-starter-test'
     integrationTestImplementation 'org.springframework.boot:spring-boot-starter-logging'
     integrationTestImplementation 'com.fasterxml.jackson.core:jackson-core'