Updated golandci-lint to 1.21.0

Signed-off-by: Michał Matczuk <michal@scylladb.com>

.golangci.yml

@@ -4,20 +4,33 @@ run:
   silent: true
 
 linters-settings:
+  errcheck:
+    check-blank: true
+  gocognit:
+    min-complexity: 50
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - performance
+      - style
   lll:
     line-length: 180
 
 linters:
   enable-all: true
   disable:
-  - gas
-  - interfacer
-  - maligned
-  - nakedret
+    - funlen
+    - gas
+    - gochecknoglobals
+    - interfacer
+    - maligned
+    - nakedret
+    - stylecheck
+    - wsl
 
 issues:
   exclude-use-default: false
   exclude:
-  - composite literal uses unkeyed fields
-  - Error return value of `.+\.Close` is not checked
-  - method Json should be JSON
+    - composite literal uses unkeyed fields
+    - Error return value of `.+\.Close` is not checked
+    - method Json should be JSON