Update dependency io.github.sparsick.testcontainers.gitserver:testcontainers-gitserver to v0.15.0 (jenkinsci#1759)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

pom.xml

@@ -194,7 +194,7 @@
     <dependency>
       <groupId>io.github.sparsick.testcontainers.gitserver</groupId>
       <artifactId>testcontainers-gitserver</artifactId>
-      <version>0.14.0</version>
+      <version>0.15.0</version>
       <scope>test</scope>
       <exclusions>
         <exclusion>