phpstan support (#250)

* phpstan v1 + workflow

* Fix intend

* More fixes

* Update phpstan.neon

* phpstan level 2

* Move errors ignoring into phpstan.neon

* phpstan level 3

* Don't ignore templates folder

* Something from level 4

* Update phpstan.neon

.github/workflows/phpstan.yml

@@ -0,0 +1,47 @@
+name: "PHPStan"
+
+on:
+  pull_request:
+    branches: [develop]
+  push:
+    branches: [develop]
+
+jobs:
+  tests:
+    name: PhpStan on PHP ${{ matrix.php-versions }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php-versions: [ '8.1', '8.2', '8.3' ]
+    steps:
+      - name: "Checkout"
+        uses: "actions/checkout@v4"
+
+      - name: "Install PHP"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "none"
+          extensions: "intl, zip"
+          ini-values: "memory_limit=-1"
+          php-version: "${{ matrix.php-version }}"
+
+      - name: Get composer cache directory
+        id: composer-cache
+        run: echo "dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
+
+      - name: Cache composer dependencies
+        uses: actions/cache@v4
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          # Use composer.json for key, if composer.lock is not committed.
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
+          #key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: ${{ runner.os }}-composer-${{ hashFiles('**/composer.json') }}
+
+      - name: "Install composer dependencies"
+        run: "composer install"
+
+      - name: "Run PHPStan"
+        run: "/usr/bin/php vendor/bin/phpstan analyse"