Bump up golangci-lint to v1.49

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

.github/workflows/tests.yml

@@ -64,7 +64,7 @@ jobs:
     - name: golangci-lint
       uses: golangci/golangci-lint-action@v3
       with:
-        version: v1.47
+        version: v1.49
         args: --verbose
 
   project:

.golangci.yml

@@ -1,7 +1,5 @@
 linters:
   enable:
-    - structcheck
-    - varcheck
     - staticcheck
     - unconvert
     - gofmt