golangci: disable new exhauststruct rule

A new linter rule was added in the latest version that wants all fields
in a struct to be declared, even if the default value is used. Because
that would mean a large diff for us, we disable the rule for now.

.golangci.yml

@@ -108,6 +108,7 @@ linters:
   - contextcheck
   - errname
   - exhaustivestruct
+  - exhaustruct
   - goerr113
   - gomnd
   - ifshort