Require older werkzeug for now for empty file test

Current werkzeug fails if given an empty file as
input; hold at 2.2 for now. See also
pallets/werkzeug#2740.

.github/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
-        pip install coverage scons flask flake8 bokeh
+        pip install coverage scons flask<2.3 werkzeug<2.3 flake8 bokeh
         git clone --depth=5 https://github.com/salilab/saliweb
         export PYTHON=`pip show coverage |grep Location|cut -b11-`
         (cd saliweb && scons modeller_key=UNKNOWN pythondir=$PYTHON perldir=~/perl prefix=~/usr webdir=~/www install && touch $PYTHON/saliweb/frontend/config.py)