github-ci: add Tarantool 2.10

Add Tarantool 2.10 [1] to testing matrix, it is a first release with
datetime support. Tarantool 2.9 has been removed, it was never
published [2].

1. https://www.tarantool.io/en/doc/latest/release/2.10.0/
2. https://www.tarantool.io/en/doc/latest/release/calendar/

Needed for #118

Author: ligurio

.github/workflows/testing.yml

@@ -29,7 +29,7 @@ jobs:
         tarantool:
           - '1.10'
           - '2.8'
-          - '2.9'
+          - '2.10'
           - '2.x-latest'
         coveralls: [false]