Revert "Update path used to activate venv."

This reverts commit 431933d.

We cannot change this yet, as we’re still on 9.4.  (Also it should use
`uv run`.)

Signed-off-by: Anders Kaseorg <[email protected]>

Author: andersk

Dockerfile

@@ -39,7 +39,7 @@ ARG CUSTOM_CA_CERTIFICATES
 
 # Finally, we provision the development environment and build a release tarball
 RUN SKIP_VENV_SHELL_WARNING=1 ./tools/provision --build-release-tarball-only
-RUN . ./.venv/bin/activate && \
+RUN . /srv/zulip-py3-venv/bin/activate && \
     ./tools/build-release-tarball docker && \
     mv /tmp/tmp.*/zulip-server-docker.tar.gz /tmp/zulip-server-docker.tar.gz