not build on tags, release already built in future

currently 2 builds happen, one for the main branch, one for the tag.
this should not be necessary, one build is sufficient, producing a
verison including the git hash. this can be converted to a release
later on, and ripme.json updated to this build.

the release procedure is thus: first commit, and let it build,
second, create a tag like '2.0.4' and mark the release as official,
then push an updated ripme.json with the version 2.0.4-12-487e38cc
to trigger clients prompting to updating ifself when it is run.

.github/workflows/gradle.yml

@@ -1,6 +1,12 @@
 name: CI + release
 
-on: [push, pull_request]
+on:
+  pull_request:
+  push:
+    branches:
+      - '**'
+    tags:
+      - '!**'
 
 jobs:
   build:

src/main/java/com/rarchives/ripme/ui/UpdateUtils.java

@@ -45,7 +45,14 @@ public class UpdateUtils {
     }
 
     private static String getUpdateJarURL(String latestVersion) {
-        return "https://github.com/" + REPO_NAME + "/releases/download/" + latestVersion + "/ripme-" + latestVersion + ".jar";
+        // this works with a tag created in github, and thus download URLs like:
+        // https://github.com/ripmeapp2/ripme/releases/download/2.0.4/ripme-2.0.4-12-487e38cc.jar
+        return "https://github.com/"
+                + REPO_NAME
+                + "/releases/download/"
+                + latestVersion.substring(0, latestVersion.indexOf("-"))
+                + "/ripme-"
+                + latestVersion + ".jar";
     }
 
     public static String getThisJarVersion() {