Add Julia 1.7 and Julia 1.8 to test matrix

Author: mkitti

.github/workflows/main.yml

@@ -24,7 +24,8 @@ jobs:
         julia-version:
           - '1.0'
           - '1.6'
-          - '~1.7.0-rc1'
+          - '1.7'
+          - '1.8'
           - 'nightly'
         exclude:
           - os: ubuntu-latest