feat: Unpin xmlsec and lxml.

We are now on Python 3.11 and running tests
on the latest version of Ubuntu, which seems to mean
we don't need these pins anymore. In fact, it seems
to break while on these pins.

scripts/structures_pruning/requirements/base.txt

@@ -11,7 +11,7 @@ click==8.1.6
     #   click-log
 click-log==0.4.0
     # via -r scripts/structures_pruning/requirements/base.in
-dnspython==2.6.1
+dnspython==2.7.0
     # via pymongo
 edx-opaque-keys==2.11.0
     # via -r scripts/structures_pruning/requirements/base.in

scripts/structures_pruning/requirements/testing.txt

@@ -12,7 +12,7 @@ click-log==0.4.0
     # via -r scripts/structures_pruning/requirements/base.txt
 ddt==1.7.2
     # via -r scripts/structures_pruning/requirements/testing.in
-dnspython==2.6.1
+dnspython==2.7.0
     # via
     #   -r scripts/structures_pruning/requirements/base.txt
     #   pymongo