Bump lxml from 5.3.0 to 6.1.0 in /tests/scripts/thread-cert (#12958)

Bumps [lxml](https://github.com/lxml/lxml) from 5.3.0 to 6.1.0.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](https://github.com/lxml/lxml/compare/lxml-5.3.0...lxml-6.1.0)

---
updated-dependencies:
- dependency-name: lxml
  dependency-version: 6.1.0
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

tests/scripts/thread-cert/requirements.txt

@@ -4,9 +4,11 @@
 #
 #    pip-compile requirements.in
 #
+appdirs==1.4.4
+    # via pyshark
 ipaddress==1.0.23
     # via -r requirements.in
-lxml==5.3.0
+lxml==6.1.0
     # via pyshark
 packaging==23.0
     # via pyshark
@@ -14,9 +16,9 @@ pexpect==4.8.0
     # via -r requirements.in
 ptyprocess==0.7.0
     # via pexpect
-py==1.11.0
-    # via pyshark
 pycryptodome==3.19.1
     # via -r requirements.in
 pyshark==0.6
     # via -r requirements.in
+termcolor==3.3.0
+    # via pyshark