Specify setup-beam@v1 vs v1.7.0 (#19)

Author: starbelly

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
         rebar3: ['3.14.1', '3.14.2', '3.14.3']
     steps:
       - uses: actions/checkout@v2
-      - uses: erlef/setup-beam@v1.7.0
+      - uses: erlef/setup-beam@v1
         with:
           otp-version: ${{matrix.otp}}
           rebar3-version: ${{matrix.rebar3}}