Add squirrel to go.mod

Author: owen-mc

go/ql/test/library-tests/semmle/go/dataflow/flowsources/local/database/go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/couchbase/gocb v1.6.7
 	github.com/couchbase/gocb/v2 v2.9.4
 	github.com/jmoiron/sqlx v1.4.0
+	github.com/Masterminds/squirrel v1.5.4
 	github.com/rqlite/gorqlite v0.0.0-20250128004930-114c7828b55a
 	go.mongodb.org/mongo-driver v1.17.3
 	gorm.io/gorm v1.25.12

go/ql/test/library-tests/semmle/go/dataflow/flowsources/local/database/vendor/modules.txt

@@ -13,6 +13,9 @@ github.com/couchbase/gocb/v2
 # github.com/jmoiron/sqlx v1.4.0
 ## explicit
 github.com/jmoiron/sqlx
+# github.com/Masterminds/squirrel v1.5.4
+## explicit
+github.com/Masterminds/squirrel
 # github.com/rqlite/gorqlite v0.0.0-20250128004930-114c7828b55a
 ## explicit
 github.com/rqlite/gorqlite