Disable depguard

depguard has switch from a deny list to an allow list, so it rejects
everything by default. Since depguard wasn't previously configured to
deny anything, this disables it entirely (no linting is lost).

Signed-off-by: Stephen Kitt <skitt@redhat.com>

.golangci.yml

@@ -3,7 +3,6 @@ linters:
   enable:
     - bodyclose
     - deadcode
-    - depguard
     - dogsled
     - dupl
     - errcheck