CI: remove the temporary pandas RC build (#2331)

.github/workflows/tests.yaml

@@ -60,9 +60,6 @@ jobs:
             os: windows-latest
             postgis: false
             dev: false
-          - env: ci/envs/39-rc.yaml
-            os: ubuntu-latest
-            dev: true
           - env: ci/envs/310-dev.yaml
             os: ubuntu-latest
             dev: true

ci/envs/39-rc.yaml

@@ -1,32 +0,0 @@
-name: test
-channels:
-  - conda-forge
-dependencies:
-  - python=3.9
-  - cython
-  # required
-  - shapely
-  - fiona
-  - pyproj
-  - packaging
-  # testing
-  - pytest
-  - pytest-cov
-  - pytest-xdist
-  - fsspec
-  # optional
-  - rtree
-  - matplotlib-base
-  - mapclassify
-  - folium
-  - xyzservices
-  - scipy
-  - geopy
-  #- geopy
-  - SQLalchemy
-  - libspatialite
-  - pyarrow
-  - pip
-  - pip:
-    # dev versions of packages
-    - git+https://github.com/pydata/pandas.git@1.4.x