added 2021.1.23f1 as testing editor

.yamato/environments.yml

 upmci_registry: https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-npm
 
 coverage_editors:
-#   - version: 2019.4.18f1
+  - version: 2021.1.23f1
-#   - version: 2019.4.18f1
+  - version: 2021.1.23f1
-#   - version: 2019.4.18f1
+  - version: 2021.1.23f1
-#  - version: 2019.4.18f1
+  - version: 2021.1.23f1
 
 publish_platforms:
   - name: win