chore: refactor codebase and update linter configuration

- Remove `deadcode`, `depguard`, `exportloopref`, `structcheck`, and `varcheck` linters from the configuration

Signed-off-by: appleboy <[email protected]>

Author: appleboy

.golangci.yml

@@ -4,12 +4,9 @@ linters:
   fast: false
   enable:
     - bodyclose
-    - deadcode
-    - depguard
     - dogsled
     - dupl
     - errcheck
-    - exportloopref
     - exhaustive
     - gochecknoinits
     - goconst
@@ -29,13 +26,11 @@ linters:
     - nolintlint
     - rowserrcheck
     - staticcheck
-    - structcheck
     - stylecheck
     - typecheck
     - unconvert
     - unparam
     - unused
-    - varcheck
     - whitespace
     - gofumpt