CI: Update linter config for current linter version

Signed-off-by: Knut Ahlers <knut@ahlers.me>

.golangci.yml

@@ -9,7 +9,9 @@ run:
   modules-download-mode: readonly
 
 output:
-  format: tab
+  formats:
+    - format: tab
+      path: stdout
 
 issues:
   # This disables the included exclude-list in golangci-lint as that
@@ -75,9 +77,7 @@ linters-settings:
     min-complexity: 15
 
   gomnd:
-    settings:
-      mnd:
-        ignored-functions: 'strconv.(?:Format|Parse)\B+'
+    ignored-functions: 'strconv.(?:Format|Parse)\B+'
 
   revive:
     rules: