Update golangci-lint version and fix reports

This commit updates golangci-lint to v1.44.0.
It also removes deprecated golint in favour of revive linter.
Finally, it addresses an issue reported by linter.

Signed-off-by: Milos Gajdos <milosthegajdos@gmail.com>

.golangci.yml

@@ -6,7 +6,7 @@ linters:
     - unconvert
     - gofmt
     - goimports
-    - golint
+    - revive
     - ineffassign
     - vet
     - unused

context/http.go

@@ -246,9 +246,7 @@ func (ctx *muxVarsContext) Value(key interface{}) interface{} {
 			return ctx.vars
 		}
 
-		if strings.HasPrefix(keyStr, "vars.") {
-			keyStr = strings.TrimPrefix(keyStr, "vars.")
-		}
+		keyStr = strings.TrimPrefix(keyStr, "vars.")
 
 		if v, ok := ctx.vars[keyStr]; ok {
 			return v

script/setup/install-dev-tools

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-GOLANGCI_LINT_VERSION="v1.27.0"
+GOLANGCI_LINT_VERSION="v1.44.0"
 
 #
 # Install developer tools to $GOBIN (or $GOPATH/bin if unset)