chore: update Go to 1.26.4 (#144)

Bump the go directive in go.mod from 1.25.7 to the latest stable Go
release, 1.26.4. CI workflows use go-version-file: 'go.mod', so they
pick up the new version automatically.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ChrisJBurns

go.mod

@@ -1,6 +1,6 @@
 module github.com/stackloklabs/gofetch
 
-go 1.25.7
+go 1.26.4
 
 require (
 	github.com/JohannesKaufmann/html-to-markdown/v2 v2.5.1