gh test - use specific nim version

Signed-off-by: George Lemon <georgelemon@protonmail.com>

Author: georgelemon

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       matrix:
         nim-version:
-          - 'stable'
+          - '2.0.0'
     steps:
       - uses: actions/checkout@v3