fix: update golangci-lint config for v1.64 compatibility

Fix configuration validation errors in .golangci.yml:

Changes:
- Remove deprecated 'check-shadowing' option from govet
- Replace with new 'settings.shadow.strict' configuration
- Remove deprecated 'format' option from output section
- Keep remaining output options (print-issued-lines, print-linter-name, sort-results)

These options were deprecated in newer golangci-lint versions and
caused CI validation failures. The new configuration maintains the
same linting behavior while being compatible with golangci-lint v1.64+.

Fixes CI error:
- jsonschema validation errors for govet and output sections
- Configuration now validates successfully with golangci-lint config verify

Author: Rihoj

.golangci.yml

@@ -46,8 +46,10 @@ linters-settings:
     check-blank: false
 
   govet:
-    check-shadowing: true
     enable-all: true
+    settings:
+      shadow:
+        strict: true
 
   gocyclo:
     min-complexity: 15
@@ -102,7 +104,6 @@ issues:
       text: "SA1019:" # Ignore deprecation warnings
 
 output:
-  format: colored-line-number
   print-issued-lines: true
   print-linter-name: true
   sort-results: true