Update JOSM version to compile against (→ 12275)

build.gradle

@@ -54,12 +54,12 @@ dependencies {
    * Please check for numeric versions, if that specific version is available for download from https://josm.openstreetmap.de/download/ .
    * If not, choose the next higher number that is available, or the gradle build will break.
    */
-  implementation(':josm:12128')
+  implementation(':josm:12275')
   // For plugins it's irrelevant, which version is specified, always the latest version is used.
   requiredPlugin (name: 'apache-commons'){changing=true}
   requiredPlugin (name: 'apache-http'){changing=true}
 
-  testImplementation ':josm-unittest'
+  testImplementation (name: 'josm-unittest'){changing=true}
   testImplementation 'junit:junit:4.12'
 }