Add missing sonatype plugin to Dependabot multi-ecosystem group (#29)

Author: philipp94831

.github/dependabot.yaml

@@ -12,6 +12,7 @@ updates:
       - "gradle-wrapper"
       - "com.bakdata.release"
       - "com.bakdata.sonar"
+      - "com.bakdata.sonatype"
       - "com.bakdata.jib"
       - "com.bakdata.avro"
       - "com.bakdata.mockito"
@@ -34,6 +35,7 @@ updates:
       - dependency-name: "gradle-wrapper"
       - dependency-name: "com.bakdata.release"
       - dependency-name: "com.bakdata.sonar"
+      - dependency-name: "com.bakdata.sonatype"
       - dependency-name: "com.bakdata.jib"
       - dependency-name: "com.bakdata.avro"
       - dependency-name: "com.bakdata.mockito"