[DO NOT MERGE] only check beta for const generics

Author: cuviper

.github/workflows/pr.yaml

@@ -8,6 +8,7 @@ env:
 jobs:
 
   check:
+    if: false
     name: Check (1.36.0)
     runs-on: ubuntu-latest
     steps:
@@ -28,15 +29,15 @@ jobs:
           args: --verbose --locked
 
   test:
-    name: Test (stable)
+    name: Test (beta)
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Install
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: beta
           profile: minimal
           override: true
       - name: Build