qa: adds GHA continuous integration workflow

- Adds the laminas-continuous-integration GHA workflow.
- Adds .gitattributes to shape what is installed when installed via Packagist.

.gitattributes

@@ -0,0 +1,8 @@
+/.gitattributes export-ignore
+/.github/ export-ignore
+/.gitignore export-ignore
+/composer.lock export-ignore
+/phpcs.xml.dist export-ignore
+/phpunit.xml.dist export-ignore
+/psalm.xml.dist export-ignore
+/test/ export-ignore

.github/workflows/continuous-integration.yml

@@ -0,0 +1,14 @@
+name: "Continuous Integration"
+
+on:
+  pull_request:
+  push:
+    branches:
+      - '[0-9]+.[0-9]+.x'
+      - 'refs/pull/*'
+      - 'renovate/*'
+    tags:
+
+jobs:
+  ci:
+    uses: laminas/workflow-continuous-integration/.github/workflows/continuous-integration.yml@1.x