lint: replace deprecated linter names

`megacheck` has been deprecated/split into `gosimple`, `staticcheck`,
and `unused`, which we're already using.

https://github.com/golangci/golangci-lint/blob/d2b439faa53bc7d0645049c3e23fc858736b8cc4/pkg/lint/lintersdb/validator_test.go#L227

`vet` is now `govet`.

https://github.com/golangci/golangci-lint/blame/d2b439faa53bc7d0645049c3e23fc858736b8cc4/pkg/lint/lintersdb/validator_test.go#L228

For more context, see: golangci/golangci-lint#4562

Signed-off-by: Laura Brehm <[email protected]>

Author: laurazard

.golangci.yml

@@ -16,7 +16,6 @@ linters:
     - govet
     - ineffassign
     - lll
-    - megacheck
     - misspell      # Detects commonly misspelled English words in comments.
     - nakedret
     - nilerr        # Detects code that returns nil even if it checks that the error is not nil.
@@ -36,7 +35,7 @@ linters:
     - unparam
     - unused
     - usestdlibvars
-    - vet
+    - govet
     - wastedassign
 
   disable: