fix: fiona/gdal issue [#213](conda-forge/fiona-feedstock#213) on windows

This issue seems to be related to pinnings under windows and fiona resulting in the following fiona error:
Traceback (most recent call last):
File , line 1, in
File C:\tools\miniconda3\envs\fiona_test\Lib\site-packages\fiona_init_.py, line 86, in
from fiona._env import (
ImportError: DLL load failed while importing _env: The specified procedure could not be found.

As a circumention, install fiona with pip, as suggested by https://stackoverflow.com/a/77289885/4556479

environment.yml

@@ -9,7 +9,7 @@ channels:
 dependencies:
   - python>=3.7
   - pip
-  - fiona==1.8.22 # pin until fiona-feedstock/issues/213 is solved; only necessary for windows
+  # - fiona==1.8.22 # pin until fiona-feedstock/issues/213 is solved; only necessary for windows
   - shapely
   - pandas>=0.24.2
   - pyproj>=2.0.0
@@ -19,4 +19,7 @@ dependencies:
   - hdbscan>=0.8.31
   - seaborn
   - scipy
+  - gdal
+  pip:
+    - fiona