[hotfix] Add release tools as submodule

diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..e5d40f3
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,4 @@
+[submodule "tools/releasing/shared"]
+	path = tools/releasing/shared
+	url = https://github.com/apache/flink-connector-shared-utils
+	branch = release_utils
diff --git a/tools/releasing/shared b/tools/releasing/shared
new file mode 160000
index 0000000..f6985af
--- /dev/null
+++ b/tools/releasing/shared
@@ -0,0 +1 @@
+Subproject commit f6985affda63eac5c66864010d20afcb70dce112