Installing specific fontconfig on mac.

I stumbled across this, which suggested this workaround:
kb47/pdf-poppler#2 (comment)

RE:natcap#249 natcap#252

.github/workflows/pythonpackage.yml

@@ -16,10 +16,6 @@ jobs:
         python-version: [3.7, 3.8, 3.9]
         gdal: ["3.2.2", "3.3.0", "3.4.0"]
         os: [ubuntu-latest, windows-latest, macos-latest]
-        # Fontconfig, poppler needed for binary build issues on mac.
-        # Specfically, see natcap/pygeoprocessing#252
-        fontconfig: ["2.13.96"]
-        poppler: ["21.11.0"]
 
         include:
           - python-version: "3.10"
@@ -74,9 +70,16 @@ jobs:
             # Installing all of these in the same line will force conda to
             # resolve all requirements at once, reducing the chance of DLL
             # conflicts.
-            conda install --file requirements.txt gdal==${{ matrix.gdal }} fontconfig==${{ matrix.fontconfig }} poppler==${{ matrix.poppler }} setuptools build
+            conda install --file requirements.txt gdal==${{ matrix.gdal }} setuptools build
             python -m build --wheel
             python -m pip install $(find dist -name "*.whl")
 
+      - name: Mac dylib hack
+        if: matrix.os == 'macos-latest'
+        run: |
+            # Specific fontconfig needed for binary build issues on mac.
+            # See natcap/pygeoprocessing#252
+            conda install fontconfig=2.13.1
+
       - name: Test with pytest
         run: pytest