chore: normalize lang_version to use quotes

Author: service-bot-app[bot]

service.yml

@@ -1,6 +1,6 @@
 name: kafka-streams-examples
 lang: java
-lang_version: 8
+lang_version: "8"
 code_artifact:
   enable: true
   package_paths:
@@ -77,4 +77,4 @@ semaphore:
           description: 'Skip publishing community docker images'
           options:
             - 'True'
-            - 'False'
+            - 'False'