Fix broken workflows

Dropped testing from unsupported python versions (3.7 and 3.8, so we only test
on 3.9 - 3.11 for now); also added pyyaml to dev-feisty environment since
github actions were failing with

ModuleNotFoundError: No module named 'yaml'

.github/workflows/ci.yaml

@@ -21,7 +21,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ['ubuntu-latest']
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.9', '3.10', '3.11']
     steps:
       - uses: actions/checkout@v2
         with:

.github/workflows/ci2.yaml

@@ -16,7 +16,6 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        # python-version: [3.8]
     steps:
       - uses: actions/checkout@v2
 

ci/environment.yml

@@ -24,6 +24,7 @@ dependencies:
   - pre-commit
   - pytest
   - pytest-cov
+  - pyyaml
   - scipy
   - xarray
   - zarr