docs(action): explicitly mark all optional inputs with required: false (#737)

Co-authored-by: Kranthi Poturaju <Kranthi.Poturaju1@aexp.com>

action.yml

@@ -7,18 +7,25 @@ branding:
 inputs:
   dotnet-version:
     description: 'Optional SDK version(s) to use. If not provided, will install global.json version when available. Examples: 2.2.104, 3.1, 3.1.x, 3.x, 6.0.2xx, latest'
+    required: false
   dotnet-quality:
     description: 'Optional quality of the build. The possible values are: daily, preview, ga.'
+    required: false
   dotnet-channel:
     description: 'Optional channel for the installation. The possible values are: STS, LTS, A.B (e.g. 8.0), A.B.Cxx (e.g. 8.0.1xx, available since 5.0). To be used with "dotnet-version: latest".'
+    required: false
   global-json-file:
     description: 'Optional global.json location, if your global.json isn''t located in the root of the repo.'
+    required: false
   source-url:
     description: 'Optional package source for which to set up authentication. Will consult any existing NuGet.config in the root of the repo and provide a temporary NuGet.config using the NUGET_AUTH_TOKEN environment variable as a ClearTextPassword'
+    required: false
   owner:
     description: 'Optional OWNER for using packages from GitHub Package Registry organizations/users other than the current repository''s owner. Only used if a GPR URL is also provided in source-url'
+    required: false
   config-file:
     description: 'Optional NuGet.config location, if your NuGet.config isn''t located in the root of the repo.'
+    required: false
   cache:
     description: 'Optional input to enable caching of the NuGet global-packages folder'
     required: false