remove deprecated golangci-lint linters

Linters 'deadcode' and 'varcheck' are deprecated since v1.49.0
and had been replaced by 'unused'

.golangci.yml

@@ -7,7 +7,6 @@ run:
 
 linters:
   enable:
-    - deadcode
     - depguard
     - gofmt
     - goimports
@@ -17,10 +16,10 @@ linters:
     - ineffassign
     - misspell
     - typecheck
-    - varcheck
     - errname
     - makezero
     - whitespace
+    - unused
   disable-all: true
 
 linters-settings:

hack/lint.Dockerfile

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1
 
 ARG GO_VERSION="1.20"
-ARG GOLANGCI_LINT_VERSION="v1.48"
+ARG GOLANGCI_LINT_VERSION="v1.51"
 
 FROM golang:${GO_VERSION}-alpine AS base
 ENV GOFLAGS="-buildvcs=false"