version based on the git repository

This commit remove the need to update the brand for GIT_URL and GIT_BRANCH:
there are read from the git repository.

It is possible to call python -m searx.version freeze to freeze the current version.
Useful when the code is installed outside git (distro package, docker, etc...)

Dockerfile

@@ -60,9 +60,6 @@ ARG VERSION_GITCOMMIT=unknown
 RUN su searx -c "/usr/bin/python3 -m compileall -q searx"; \
     touch -c --date=@${TIMESTAMP_SETTINGS} searx/settings.yml; \
     touch -c --date=@${TIMESTAMP_UWSGI} dockerfiles/uwsgi.ini; \
-    if [ ! -z $VERSION_GITCOMMIT ]; then\
-      echo "VERSION_STRING = VERSION_STRING + \"-$VERSION_GITCOMMIT\"" >> /usr/local/searx/searx/version.py; \
-    fi; \
     find /usr/local/searx/searx/static -a \( -name '*.html' -o -name '*.css' -o -name '*.js' \
     -o -name '*.svg' -o -name '*.ttf' -o -name '*.eot' \) \
     -type f -exec gzip -9 -k {} \+ -exec brotli --best {} \+