update build dependencies, including all we need

Now the list includes all dependencies we need, even if the build image
we're building on already has some of these installed. Hopefully this
has a documentation benefit and makes future updates to later OS images
easier.

Author: wnienhaus

.github/workflows/run_tests.yaml

@@ -13,7 +13,7 @@ jobs:
     - name: Install dependencies
       run: |
         sudo apt-get update
-        sudo apt-get install -y libffi-dev pkg-config bison flex
+        sudo apt-get install -y git build-essential libffi-dev pkg-config python3 bison flex
 
     - name: Record version
       run: |