Update to Go1.25

Signed-off-by: beorn7 <beorn@grafana.com>

Author: beorn7

.circleci/config.yml

@@ -6,7 +6,7 @@ executors:
   # Whenever the Go version is updated here, .promu.yml should also be updated.
   golang:
     docker:
-      - image: cimg/go:1.24
+      - image: cimg/go:1.25
 jobs:
   test:
     executor: golang

.promu.yml

@@ -2,7 +2,7 @@
 go:
     # Whenever the Go version is updated here
     # .circle/config.yml should also be updated.
-    version: 1.24
+    version: 1.25
 repository:
     path: github.com/prometheus/prom2json
 build: