.golangci.yml: don't lint autogenerated files

So when we enable linters for formatting, they do not complain about
those files.

Refs #9557

Signed-off-by: Mateusz Gozdek <mgozdekof@gmail.com>

.golangci.yml

@@ -1,5 +1,8 @@
 run:
   deadline: 5m
+  skip-files:
+    # Skip autogenerated files.
+    - ^.*\.(pb|y)\.go$
 
 linters:
   enable: