bump golang to 1.25.4 & golangci-lint to 2.6.0 (#35)

bump golang to 1.25.4

Author: nocive

.github/workflows/ci.yml

@@ -43,7 +43,7 @@ jobs:
     strategy:
       matrix:
         go: ["1.25"]
-        lint: ["v2.5"]
+        lint: ["v2.6"]
     name: lint
     runs-on: ubuntu-latest
     steps:

go.mod

@@ -1,6 +1,6 @@
 module github.com/simplesurance/dependencies-tool/v3
 
-go 1.25.3
+go 1.25.4
 
 require (
 	github.com/awalterschulze/gographviz v2.0.3+incompatible