match/match_test.go: Fix import

This test was not building, as relative imports are not allowed when using modules

Change-Id: I661870c0d676029a782fe2a05acb98d4544fbb95
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/52502
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>

tools/src/match/match_test.go

@@ -18,7 +18,7 @@ import (
 	"strings"
 	"testing"
 
-	match "."
+	"dawn.googlesource.com/tint/tools/src/match"
 )
 
 func TestMatch(t *testing.T) {