limit git tasks to main branch

Taskfile.yml

@@ -5,13 +5,19 @@ vars:
     sh: svu next --strip-prefix
   VERSIONFILE: version.txt
   COMMITMSG: "chore: bump version to v{{.RELEASE}}"
+  CURRENTBRANCH:
+    sh: git branch --show-current
 
 tasks:
   release:tag:
+    preconditions:
+      - test {{.CURRENTBRANCH}} == "main"
     cmds:
       - git tag v{{.RELEASE}}
 
   release:file:
+    preconditions:
+      - test {{.CURRENTBRANCH}} == "main"
     cmds:
       - echo {{.RELEASE}} >{{.VERSIONFILE}}
       - git add {{.VERSIONFILE}}