chore: bump go directive to 1.25.7 to satisfy new omni transitive deps

The omni bump in the previous commit pulls in a transitive closure that
requires Go ≥ 1.25.7. `go mod tidy` raises the main module's go directive
accordingly, which CI verifies. Reverting it manually to 1.25.5 caused
both the test job's tidy-diff check and the golangci-lint context loader
to fail.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: h3n4l

go.mod

@@ -1,6 +1,6 @@
 module github.com/bytebase/gomongo
 
-go 1.25.5
+go 1.25.7
 
 require (
 	github.com/bytebase/omni v0.0.0-20260509021101-01140a7b9722