bump superdesk-core and fix eve events issues (#1009)

* bump superdesk-core

- make getattr only handle `on_` callbacks as events
- fix issues that were hidden due to it

* use superdesk-core v2.7.3

.github/workflows/tests.yml

@@ -27,10 +27,8 @@ jobs:
              sudo apt-get update
              sudo apt-get install pkg-config libxml2-dev libxmlsec1-dev libxmlsec1-openssl
 
-      - name: pip install
-        run: |
-             python -m pip install --upgrade pip wheel setuptools
-             pip install -r dev-requirements.txt
+      - run: python -m pip install --upgrade pip wheel setuptools
+      - run: python -m pip install -r dev-requirements.txt
 
       - name: pytest
         run: pytest --ignore=tests/aap/ --disable-pytest-warnings --cov=newsroom

dev-requirements.in

@@ -0,0 +1,11 @@
+-r requirements.txt
+-r mypy-requirements.txt
+-r black-requirements.txt
+
+flake8
+pytest
+pytest-cov
+pytest-mock
+responses>=0.10.6,<0.26
+httmock
+wooper