build: bump Go toolchain to go1.25.11 (stdlib CVE fix) (#39)

govulncheck/osv-scan flag the go1.25.10 stdlib CVEs (GO-2026-5038/5039)
on master. Same one-line toolchain bump already landed on api + worker.
No code changes.

Co-authored-by: Manas Srivastava <[email protected]>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mastermanas805

go.mod

@@ -2,7 +2,7 @@ module instant.dev/provisioner
 
 go 1.25.0
 
-toolchain go1.25.10
+toolchain go1.25.11
 
 require (
 	github.com/go-redis/redismock/v9 v9.2.0