PLAYGROUND_* inputs aren't actually required

GitHub will happily still run if you don't give them, (and works just fine: see
https://github.com/SuffolkLITLab/docassemble-AssemblyLine/blob/f70ded5c029efd82e8d354d650fa02066422db8f/.github/workflows/run_form_tests.yml#L34-L36
) but it does give erraneous warnings in VSCode, if you have the GitHub actions
extension.

action.yml

@@ -7,13 +7,13 @@ inputs:
     required: true
   PLAYGROUND_EMAIL:
     description: 'The email of your docassemble testing account. This should be in your GitHub SECRETS or the SECRETS of your org.'
-    required: true
+    required: false
   PLAYGROUND_PASSWORD:
     description: 'The password of your docassemble testing account. This should be in your GitHub SECRETS or the SECRETS of your org.'
-    required: true
+    required: false
   PLAYGROUND_ID:
     description: 'The id of your docassemble testing account. This should be in your GitHub SECRETS or the SECRETS of your org.'
-    required: true
+    required: false
   DOCASSEMBLE_DEVELOPER_API_KEY:
     description: 'API key of the testing account with developer permissions on your docassemble server.'
     required: true