fix: exclude underscore-prefixed partials from sitemap (#2575)

* test: point directory-parser at underscore-exclusion PR branch

Temporarily install canonicalwebteam.directory-parser from the
exclude-underscore-prefixed-partials branch so the sitemap fix (which
drops _-prefixed partials like /maas/_tutorial and /tests/_thank-you)
can be QA'd on a demo before the package is released.

Revert to a pinned release version once the upstream PR is merged.

* chore: update directory parser module

Author: Onibenjo

requirements.txt

@@ -6,7 +6,7 @@ canonicalwebteam.templatefinder==1.0.0
 canonicalwebteam.discourse==7.1.1
 canonicalwebteam.search==2.1.2
 canonicalwebteam.form-generator==2.2.0
-canonicalwebteam.directory-parser==1.2.10
+canonicalwebteam.directory-parser==1.2.11
 canonicalwebteam.markdown-response==0.2.0
 bleach==5.0.1
 markdown==3.8.2