chore(deps): update dependency go to v1.25.6 (#143)

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

go.mod

@@ -2,7 +2,7 @@ module github.com/stackitcloud/stackit-cert-manager-webhook
 
 go 1.25.0
 
-toolchain go1.25.5
+toolchain go1.25.6
 
 // Do not remove this comment:
 // please place any replace statements here at the top for visibility and add a