ci: replace modernize job with golangci linters

Instead of using a standalone modernize (and a separate job), add
modernize and go vet (which should be same-as/similar-to go fix) linters
to golangci-lint config.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

.golangci.yml

@@ -15,6 +15,8 @@ linters:
   enable:
     - errorlint
     - forbidigo
+    - govet
+    - modernize
     - nolintlint
     - unconvert
     - unparam