use ubuntu 16.04 instead

.github/workflows/build.yml

@@ -7,7 +7,7 @@ on:
       - "v*"
 jobs:
   linux:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-16.04
     steps:
       - uses: actions/checkout@v1
         with:
@@ -29,13 +29,13 @@ jobs:
           sudo apt-get install libgeos-dev
 
           # for wxPython
-          sudo apt-get install glib-networking libsdl1.2-dev
+          sudo apt-get install glib-networking libsdl2-dev
 
           # for PyGObject
           sudo apt install libgirepository1.0-dev
 
           # wxPython doen't publish linux wheels in pypi
-          wget -q https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-18.04/wxPython-4.0.7-cp27-cp27mu-linux_x86_64.whl
+          wget -q https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-16.04/wxPython-4.0.7-cp27-cp27mu-linux_x86_64.whl
           pip install wxPython*.whl
 
           # We can't use the shapely wheel because it includes the geos