Fix PDF builds

Author: NickVolynkin

.github/workflows/deploy-branch.yml

@@ -37,6 +37,8 @@ jobs:
       - run: cmake .
       - run: make pull-modules
       - run: make build-modules
+      - run: make pdf
+      - run: make pdf-ru
       - run: make json
       - run: make json-ru
       - run: bash upload_output.sh

pdf/conf.py

@@ -9,6 +9,8 @@
     'sphinx.ext.imgmath',
     'sphinx.ext.ifconfig',
     'sphinx.ext.intersphinx',
+    'sphinx.ext.extlinks',
+    'sphinxcontrib.plantuml',
     'sphinxcontrib.rsvgconverter',
     'ext.custom',
     'ext.LuaDomain',