chore(test): use submodule in interop tests

Author: puzpuzpuz

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "test/interop"]
+	path = test/interop
+	url = [email protected]:questdb/questdb-client-test.git

sender_interop_test.go

@@ -119,7 +119,7 @@ func TestClientInterop(t *testing.T) {
 }
 
 func readTestCases() (testCases, error) {
-	file, err := os.Open("./test/ilp-client-interop-test.json")
+	file, err := os.Open("./test/interop/ilp-client-interop-test.json")
 	if err != nil {
 		return nil, err
 	}