[CI] Removed beta channel from testing temporarily

Author: Emoun

.github/workflows/rust.yml

@@ -21,7 +21,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust-version: ['1.65.0', stable, beta, nightly]
+        rust-version: ['1.65.0', stable, nightly]
 
     steps:
       - uses: actions/checkout@v2