[Chore] Introduce psalm (#962)

* chore: introduce psalm

* chore: remove dead code

* chore: run psalm workflow

* chore: run psalm in grumphp

* normalize composer.json

* chore: analyse --> analyze

* chore: just remove psalm when running tests instead of worrying about dependency mismatch hell

Co-authored-by: mr-feek <[email protected]>

composer.json

@@ -35,7 +35,8 @@
         "mockery/mockery": "^1.3",
         "orchestra/testbench": "^3 || ^4 || ^5",
         "phpro/grumphp": "^0.17.1",
-        "squizlabs/php_codesniffer": "^3.5"
+        "squizlabs/php_codesniffer": "^3.5",
+        "vimeo/psalm": "^3.12"
     },
     "extra": {
         "branch-alias": {
@@ -58,6 +59,7 @@
         }
     },
     "scripts": {
+        "analyze": "psalm",
         "check-style": "phpcs -p --standard=PSR2 src/",
         "fix-style": "phpcbf -p --standard=PSR2 src/",
         "test": "phpunit"