chore(deps): update dependency signxml to v4 (#12459)

* chore(deps): update dependency signxml to v4

* update to minimum lxml

* Update requirements.txt

---------

Co-authored-by: Katie McLaughlin <katie@glasnt.com>

Author: renovate-bot

cloud-media-livestream/keypublisher/requirements.txt

@@ -1,11 +1,11 @@
 Flask==2.2.5
 functions-framework==3.5.0
 google-cloud-secret-manager==2.21.1
-lxml==4.9.4
+lxml==5.2.1
 pycryptodome==3.21.0
-pyOpenSSL==24.0.0
+pyOpenSSL==24.3.0
 requests==2.32.2
-signxml==3.2.0
+signxml==4.0.3
 pytest==8.2.0
 pytest-mock==3.14.0
 Werkzeug==3.0.6