Update pyproject.toml and tox.ini from core

pyproject.toml

@@ -5,7 +5,7 @@ packages = [
     { include = "aleksis" }
 ]
 readme = "README.rst"
-include = ["CHANGELOG.rst", "LICENCE.rst", "aleksis/**/locale/*.mo"]
+include = ["CHANGELOG.rst", "LICENCE.rst", "aleksis/**/*.mo"]
 
 description = "AlekSIS (School Information System) — App Χρόνος (digital timetables)"
 authors = [

tox.ini

@@ -35,6 +35,7 @@ commands =
 
 [testenv:build]
 commands_pre =
+    poetry install
     poetry run sh -c "cd aleksis; aleksis-admin compilemessages"
 commands = poetry build