chore(go): bump go directive to 1.26.4 to rebuild with fixed Go stdlib (#21)

Rebuild released binaries with Go 1.26.4 to clear stdlib CVE-2026-42504,
CVE-2026-27145 and CVE-2026-42507 (all fixed in Go 1.26.4). The Alauda
release workflow uses setup-go with go-version-file: image/git-init/go.mod,
so bumping this directive is sufficient for the next -alauda-N release to
build on Go 1.26.4 and scan clean downstream in AlaudaDevops/catalog.

Author: l-qing

image/git-init/go.mod

@@ -1,6 +1,6 @@
 module github.com/tektoncd-catalog/git-clone/git-init
 
-go 1.26.3
+go 1.26.4
 
 require (
 	github.com/google/go-cmp v0.7.0