refactor: Remove psycopg2 installation from source

psycopg/psycopg2#1360 is resolved.
Installation from source no longer needed.

backend/Dockerfile

@@ -46,7 +46,7 @@ ENV PATH="$VIRTUAL_ENV/bin:$PATH"
 
 WORKDIR /tmp/backend
 RUN --mount=type=cache,id=capella-collaboration-backend-dependencies,target=/root/.cache/pip,sharing=locked \
-    pip install ".[psycopg2]"
+    pip install .
 
 RUN mkdir -p /var/log/backend && \
     chmod -R 777 /var/log/backend

backend/pyproject.toml

@@ -66,9 +66,6 @@ dev = [
   "pytest-cov",
   "aioresponses"
 ]
-psycopg2 = [
-  "psycopg2", # Need when running in a Docker container with AArch64: https://github.com/psycopg/psycopg2/issues/1360
-]
 
 [project.entry-points."capellacollab.authentication.providers"]
 oauth = "capellacollab.core.authentication.provider.oauth"