chore: enable unlambda rule from go-critic

Signed-off-by: Matthieu MOREL <[email protected]>

Author: mmorel-35

.golangci.yml

@@ -15,7 +15,6 @@ linters:
       enable-all: true
       disabled-checks:
         - hugeParam
-        - unlambda
     revive:
       rules:
         - name: unused-parameter

config/config.go

@@ -361,9 +361,7 @@ func (re *Regexp) UnmarshalYAML(unmarshal func(interface{}) error) error {
 }
 
 func substituteEnvVariables(value string) (string, error) {
-	result := os.Expand(value, func(s string) string {
-		return os.Getenv(s)
-	})
+	result := os.Expand(value, os.Getenv)
 	if result == "" {
 		return "", errors.New(value + " environment variable not found")
 	}