Rename action and update input requirements

Updated the action name and made input parameters required.

Author: fredrik0x

action.yml

@@ -1,16 +1,16 @@
-name: 'PR Security Review'
+name: 'Ethereum Security Reviewer'
 description: 'Automated security review of pull requests using LLMs'
 inputs:
   github-token:
     description: 'GitHub token for accessing PR content'
     required: true
   llm-provider:
     description: 'LLM provider to use (anthropic or openai)'
-    required: false
+    required: true
     default: 'anthropic'
   anthropic-api-key:
     description: 'Anthropic API key for Claude access'
-    required: false
+    required: true
   openai-api-key:
     description: 'OpenAI API key for GPT access'
     required: false