Move away from set-output (while updating all deps) (#148)

* Update all our deps

Get rid of warnings such as:
* `save-state` will be deprecated
* `set-output` will be deprecated
* nodejs 12 is being deprecated
...

Rely on tests to make sure the actions still works

* Fix as per CI results

* Get rid of deprecated containers

* Have a warningless run

We're not testing rebar3 here, in any case

.github/workflows/windows.yml

@@ -37,7 +37,7 @@ jobs:
             otp-version: '23'
             rebar3-version: '3.14'
             os: 'windows-latest'
-          - elixir-version: 'v1.11'
+          - elixir-version: 'v1.13'
             otp-version: '24'
             rebar3-version: '3.15'
             os: 'windows-latest'
@@ -46,7 +46,7 @@ jobs:
             rebar3-version: '3.16'
             os: 'windows-latest'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Use erlef/setup-beam
         id: setup-beam
         uses: ./
@@ -95,7 +95,7 @@ jobs:
             rebar3-version: 'nightly'
             os: 'windows-latest'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Use erlef/setup-beam
         id: setup-beam
         uses: ./