Update example env after building stable images

.github/scripts/update_example_env.py

@@ -0,0 +1,32 @@
+import os
+import re
+
+
+def get_versions():
+    frappe_version = os.getenv("FRAPPE_VERSION")
+    erpnext_version = os.getenv("ERPNEXT_VERSION")
+    assert frappe_version, "No Frappe version set"
+    assert erpnext_version, "No ERPNext version set"
+    return frappe_version, erpnext_version
+
+
+def update_env(frappe_version: str, erpnext_version: str):
+    with open("example.env", "r+") as f:
+        content = f.read()
+        for env, var in (
+            ("FRAPPE_VERSION", frappe_version),
+            ("ERPNEXT_VERSION", erpnext_version),
+        ):
+            content = re.sub(rf"{env}=.*", f"{env}={var}", content)
+        f.seek(0)
+        f.truncate()
+        f.write(content)
+
+
+def main() -> int:
+    update_env(*get_versions())
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())