Use eldev to lint the project

Useful for finding errors and warnings in the code.

Author: bbatsov

Diff for: .github/workflows/lint-emacs.yml

@@ -0,0 +1,31 @@
+name: Lint Emacs
+
+on:
+  push:
+    paths: ['**.el']
+  pull_request:
+    paths: ['**.el']
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    # continue-on-error: ${{matrix.emacs_version == 'snapshot'}}
+
+    strategy:
+      matrix:
+        emacs_version: ['snapshot']
+
+    steps:
+    - name: Set up Emacs
+      uses: purcell/setup-emacs@master
+      with:
+        version: ${{matrix.emacs_version}}
+
+    - name: Install Eldev
+      run: curl -fsSL https://raw.github.com/doublep/eldev/master/webinstall/github-eldev | sh
+
+    - name: Check out the source code
+      uses: actions/checkout@v2
+
+    - name: Lint the project
+      run: eldev -dtT -C compile --warnings-as-errors