SP-988: Update composer usage and gitattributes file

Author: p-maguire

.gitattributes

@@ -28,4 +28,3 @@
 .gitignore export-ignore
 .travis.yml export-ignore
 build.xml export-ignore
-composer.json export-ignore

modules/gateways/bitpaycheckout/composer.json

@@ -12,11 +12,5 @@
   "require": {
       "bitpay/sdk": "^9.0",
       "php": "^8.1 || ^8.2 || ^8.3"
-  },
-  "autoload": {
-    "files": ["lib/functions.php"],
-    "psr-4": {
-      "Sample\\": "lib/Sample/"
-    }
   }
 }