Add mpl build deps if testing for py35 (x86)

Author: molinav

.github/workflows/basemap-for-manylinux.yml

@@ -248,6 +248,12 @@ jobs:
         run: |
           apt-get update
           apt-get install -y gcc g++ make
+      -
+        name: Install matplotlib dependencies
+        run: |
+          apt-get update
+          apt-get install -y libfreetype6-dev libpng12-dev
+        if: matrix.arch == 'x86' && matrix.python-version == '3.5'
       -
         name: Install package
         run: |