Update NPM to npm in graphql description

app/graphql/types/packages/package_type_enum.rb

@@ -5,7 +5,7 @@ module Packages
     class PackageTypeEnum < BaseEnum
       PACKAGE_TYPE_NAMES = {
         pypi: 'PyPI',
-        npm: 'NPM'
+        npm: 'npm'
       }.freeze
       ::Packages::Package.package_types.keys.each do |package_type|

doc/api/graphql/reference/gitlab_schema.graphql

@@ -18179,7 +18179,7 @@ enum PackageTypeEnum {
   MAVEN
   """
-  Packages from the NPM package manager
+  Packages from the npm package manager
   """
   NPM

doc/api/graphql/reference/gitlab_schema.json

@@ -53370,7 +53370,7 @@
             },
             {
               "name": "NPM",
-              "description": "Packages from the NPM package manager",
+              "description": "Packages from the npm package manager",
               "isDeprecated": false,
               "deprecationReason": null
             },

doc/api/graphql/reference/index.md

@@ -5203,7 +5203,7 @@ Rotation length unit of an on-call rotation.
 | `GENERIC` | Packages from the Generic package manager |
 | `GOLANG` | Packages from the Golang package manager |
 | `MAVEN` | Packages from the Maven package manager |
-| `NPM` | Packages from the NPM package manager |
+| `NPM` | Packages from the npm package manager |
 | `NUGET` | Packages from the Nuget package manager |
 | `PYPI` | Packages from the PyPI package manager |
 | `RUBYGEMS` | Packages from the Rubygems package manager |