rfc3339-validator: replace pip package with conda

See Issue #612

Author: pont-us

environment.yml

@@ -31,6 +31,7 @@ dependencies:
   - rasterio >=1.2
   - requests >=2.25
   - requests-oauthlib >=1.3
+  - rfc3339-validator >=1.4  # for python-jsonschema date-time format validation
   - s3fs >=2021.6
   - scipy >=1.6.0
   - setuptools >=41.0
@@ -46,6 +47,3 @@ dependencies:
   - pytest >=4.4
   - pytest-cov >=2.6
   - requests-mock >=1.8.0
-  - pip
-  - pip:
-    - rfc3339-validator