chore: update Go, and linter

.golangci.yml

@@ -20,10 +20,13 @@ linters-settings:
   gofumpt:
     extra-rules: true
   depguard:
-    list-type: blacklist
-    include-go-root: false
-    packages:
-      - github.com/pkg/errors
+    rules:
+      main:
+        deny:
+          - pkg: "github.com/instana/testify"
+            desc: not allowed
+          - pkg: "github.com/pkg/errors"
+            desc: Should be replaced by standard lib errors package
   godox:
     keywords:
       - FIXME