golangci-lint: prevent io/ioutil from being used

The package has been deprecated since Go 1.16:

https://go.dev/doc/go1.16#ioutil

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.golangci.yml

@@ -12,6 +12,7 @@ linters:
     - gofmt
     - govet
     - deadcode
+    - depguard
     - goimports
     - ineffassign
     - misspell
@@ -23,6 +24,15 @@ linters:
     - structcheck
   disable-all: true
 
+linters-settings:
+  depguard:
+    list-type: blacklist
+    include-go-root: true
+    packages:
+      # The io/ioutil package has been deprecated.
+      # https://go.dev/doc/go1.16#ioutil
+      - io/ioutil
+
 issues:
   exclude-rules:
     - linters: