Ensure python 3.7 is used for sphinx and bump lerna version

.gitignore

@@ -36,9 +36,11 @@ parts
 *.pyc
 *.egg-info
 lib
+lib64
 include
 bin
 develop-eggs
+pyvenv.cfg
 
 converse-logs/*.html
 

Makefile

@@ -116,6 +116,7 @@ stamp-npm: $(LERNA) package.json package-lock.json src/headless/package.json
 .PHONY: clean
 clean:
 	npm run clean
+	rm -r lib bin include parts
 
 .PHONY: dev
 dev: stamp-npm
@@ -227,7 +228,7 @@ check: eslint dist/converse.js
 ## Documentation
 
 ./bin/activate:
-	python3 -m venv .
+	python3.7 -m venv .
 
 .installed.cfg: requirements.txt buildout.cfg
 	./bin/pip install -r requirements.txt

package.json

@@ -77,7 +77,7 @@
     "install": "^0.9.5",
     "jasmine-core": "2.99.1",
     "jsdoc": "^3.6.2",
-    "lerna": "^3.16.2",
+    "lerna": "^3.16.4",
     "lodash-template-webpack-loader": "jcbrand/lodash-template-webpack-loader",
     "mini-css-extract-plugin": "^0.7.0",
     "minimist": "^1.2.0",