Bump credentials from 2.1.5 to 2.3.8

Bumps [credentials](https://github.com/jenkinsci/credentials-plugin) from 2.1.5 to 2.3.8.
- [Release notes](https://github.com/jenkinsci/credentials-plugin/releases)
- [Changelog](https://github.com/jenkinsci/credentials-plugin/blob/master/CHANGELOG.md)
- [Commits](jenkinsci/credentials-plugin@credentials-2.1.5...credentials-2.3.8)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

pom.xml

@@ -30,7 +30,7 @@
         <groovy.eclipse.compiler.version>3.6.0-03</groovy.eclipse.compiler.version>
         <groovy.version>2.4.19</groovy.version>
         <jacoco-maven-plugin.version>0.8.5</jacoco-maven-plugin.version>
-        <jenkins-credentials.version>2.1.5</jenkins-credentials.version>
+        <jenkins-credentials.version>2.3.8</jenkins-credentials.version>
         <maven-surefire-plugin.version>2.22.2</maven-surefire-plugin.version>
 
         <mockito-core.version>2.7.22</mockito-core.version>