Added GitHub actions as CI/CD

* build tested on latest Ubuntu
* four Erlang/OTP used, as does Debian:

```
curl --silent https://packages.debian.org/search?keywords=erlang | \
    sed -ne '/Package erlang</,/<\/ul>/{/<\/a>/p; /br/p}' | \
    sed -e 's/<a.*$//' | \
    perl -0777 -pE 's/<li class="(\w+)">\n/$1/g; s/<br>([^\s]+)/$1/g; s/\+.*(?=\n)//g' | \
    sed -e '1i name otp-version' | \
    column -t

name          otp-version
buster        1:22.2.7
bullseye      1:23.2.6
bookworm      1:25.2.3
trixie        1:25.3.2.12
sid           1:25.3.2.12
experimental  1:27.0.1
```

Signed-off-by: Ariel Otilibili <[email protected]>

.github/workflows/main.yml

@@ -0,0 +1,29 @@
+name: Integration tests
+
+on:
+  pull_request:
+    branches:
+      - 'develop'
+  push:
+    branches:
+      - 'develop'
+
+jobs:
+  build:
+    name: OTP ${{ matrix.otp_version }} on ${{ matrix.os }}
+    runs-on: ${{ matrix.os }}
+    container:
+      image: erlang:${{matrix.otp_version}}
+
+    strategy:
+      matrix:
+        otp_version: ['27', '25', '23']
+        os: [ubuntu-latest]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Configure
+      run: ./configure
+    - name: Build
+      run: make