Make OTP installation optional (#81)

test-projects/gleam_gleam/.github/workflows/test.yml

@@ -0,0 +1,21 @@
+name: test
+
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2.0.0
+      - uses: erlef/setup-beam@v1.9.0
+        with:
+          otp-version: "23.2"
+          gleam-version: "0.19.0-rc3"
+      - run: gleam format --check src test
+      - run: gleam deps download
+      - run: gleam test