build: add ignoreLicenseYear option to header checker (#7651)

We are currently migrating older code from other repositories and many files there have years in the header that are not 2026.  It is OK, but the `header-checker-lint` is flagging them.

Let's disable the year validation for now.

Author: meltsufin

.github/header-checker-lint.yml

@@ -13,3 +13,4 @@ ignoreFiles:
   - "packages/*/__snapshots__/**/*.js"
   - "packages/typeless-sample-bot/test/fixtures/**/*.ts"
   - "packages/typeless-sample-bot/test/fixtures/**/*.js"
+ignoreLicenseYear: true