ci: start testing on 1.64

Author: paolobarbolini

.github/workflows/ci.yml

@@ -57,14 +57,14 @@ jobs:
     strategy:
       matrix:
         include:
-          #- name: stable
-          #  rust: stable
+          - name: stable
+            rust: stable
           - name: beta
             rust: beta
           - name: nightly
             rust: nightly
-          #- name: MSRV 1.64
-          #  rust: 1.64
+          - name: MSRV 1.64
+            rust: 1.64
 
     steps:
       - uses: actions/checkout@v2