Bump bcpkix-jdk15on from 1.69 to 1.70 (#751)

Bumps [bcpkix-jdk15on](https://github.com/bcgit/bc-java) from 1.69 to 1.70.
- [Release notes](https://github.com/bcgit/bc-java/releases)
- [Changelog](https://github.com/bcgit/bc-java/blob/master/docs/releasenotes.html)
- [Commits](https://github.com/bcgit/bc-java/commits)

---
updated-dependencies:
- dependency-name: org.bouncycastle:bcpkix-jdk15on
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

spring-cloud-gcp-security-firebase/pom.xml

@@ -31,7 +31,7 @@
         <dependency>
             <groupId>org.bouncycastle</groupId>
             <artifactId>bcpkix-jdk15on</artifactId>
-            <version>1.69</version>
+            <version>1.70</version>
             <scope>test</scope>
         </dependency>
     </dependencies>