dep: update libxml2 to v2.13.6

https://gitlab.gnome.org/GNOME/libxml2/-/releases/v2.13.6

Author: flavorjones

dependencies.yml

@@ -1,8 +1,8 @@
 ---
 libxml2:
-  version: "2.13.5"
-  sha256: "74fc163217a3964257d3be39af943e08861263c4231f9ef5b496b6f6d4c7b2b6"
-  # sha-256 hash provided in https://download.gnome.org/sources/libxml2/2.13/libxml2-2.13.5.sha256sum
+  version: "2.13.6"
+  sha256: "f453480307524968f7a04ec65e64f2a83a825973bcd260a2e7691be82ae70c96"
+  # sha-256 hash provided in https://download.gnome.org/sources/libxml2/2.13/libxml2-2.13.6.sha256sum
 
 libxslt:
   version: "1.1.42"