Test against 1.10.0alpha1 on evergreen

Author: alcaeus

.evergreen/config.yml

@@ -463,10 +463,10 @@ axes:
       # * latest-stable can be updated when we start tagging 1.10 releases (even beta)
       # * 1.10-dev can be enabled once 1.10 has been branched
       # * latest-dev can be enabled once 1.10 has been branched
-#      - id: "lowest-supported"
-#        display_name: "1.10-dev (master)"
-#        variables:
-#          EXTENSION_BRANCH: "master"
+      - id: "lowest-supported"
+        display_name: "1.10.0-alpha1"
+        variables:
+          EXTENSION_VERSION: "1.10.0alpha1"
       - id: "latest"
         display_name: "1.10-dev (master)"
         variables: