ci(dependabot): keep the endtoend testdata module up to date

The module only exists so CI can compile the committed golden code, and
that code builds against the latest version of every driver it imports.
Raise its go directive to 1.26.0, matching the other modules, since the
current releases of several of its dependencies require it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LyueKDc8vSZZALuaDh9RSq

Author: claude

.github/dependabot.yml

@@ -8,6 +8,7 @@ updates:
       - "/"
       - "/examples"
       - "/internal/goldeneye"
+      - "/internal/endtoend/testdata"
     schedule:
       interval: "daily"
     groups:

internal/endtoend/testdata/go.mod

@@ -1,6 +1,6 @@
 module github.com/sqlc-dev/sqlc/endtoend
 
-go 1.25.0
+go 1.26.0
 
 require (
 	cloud.google.com/go/spanner v1.95.1