Update go.mod to 1.21

because it requires android/soong which uses go 1.21
Bug: 3141333041
Test: go test ./...
Change-Id: I184e6165beafab337b09cd87fd02748e49c65650
diff --git a/tools/compliance/go.mod b/tools/compliance/go.mod
index 1928189..bd04077 100644
--- a/tools/compliance/go.mod
+++ b/tools/compliance/go.mod
@@ -26,4 +26,4 @@
 // Indirect dep from go-cmp
 exclude golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543
 
-go 1.18
+go 1.21