Refactor action to use composite run steps and support cross-repository issue creation

- Changed action execution from Docker to composite with Python setup.
- Added `TARGET_REPO` input to allow issue creation in a specified repository.
- Updated `GitHubClient` to use `TARGET_REPO` for issue and milestone URLs.
- Enhanced README with instructions for cross-repository usage.
- Introduced example workflow for creating TODO issues in another repository.

Signed-off-by: Shakar Bakr <5h4k4r.b4kr@gmail.com>

action.yml

@@ -2,8 +2,43 @@ name: 'TODO to Issue'
 description: 'Converts IDE TODO comments to GitHub issues'
 author: 'Alastair Mooney'
 runs:
-  using: 'docker'
-  image: 'docker://ghcr.io/alstr/todo-to-issue-action:v5.1.12'
+  using: 'composite'
+  steps:
+    - name: Set up Python
+      uses: actions/setup-python@v4
+      with:
+        python-version: '3.x'
+
+    - name: Install dependencies
+      run: pip install requests ruamel.yaml
+      shell: bash
+
+    - name: Run TODO to Issue action
+      run: python ${{ github.action_path }}/main.py
+      shell: bash
+      env:
+        INPUT_REPO: ${{ inputs.REPO }}
+        INPUT_BEFORE: ${{ inputs.BEFORE }}
+        INPUT_COMMITS: ${{ inputs.COMMITS }}
+        INPUT_DIFF_URL: ${{ inputs.DIFF_URL }}
+        INPUT_SHA: ${{ inputs.SHA }}
+        INPUT_TOKEN: ${{ inputs.TOKEN }}
+        INPUT_CLOSE_ISSUES: ${{ inputs.CLOSE_ISSUES }}
+        INPUT_AUTO_P: ${{ inputs.AUTO_P }}
+        INPUT_PROJECT: ${{ inputs.PROJECT }}
+        INPUT_PROJECTS_SECRET: ${{ inputs.PROJECTS_SECRET }}
+        INPUT_IGNORE: ${{ inputs.IGNORE }}
+        INPUT_AUTO_ASSIGN: ${{ inputs.AUTO_ASSIGN }}
+        INPUT_ACTOR: ${{ inputs.ACTOR }}
+        INPUT_ISSUE_TEMPLATE: ${{ inputs.ISSUE_TEMPLATE }}
+        INPUT_IDENTIFIERS: ${{ inputs.IDENTIFIERS }}
+        INPUT_GITHUB_URL: ${{ inputs.GITHUB_URL }}
+        INPUT_GITHUB_SERVER_URL: ${{ inputs.GITHUB_SERVER_URL }}
+        INPUT_ESCAPE: ${{ inputs.ESCAPE }}
+        INPUT_LANGUAGES: ${{ inputs.LANGUAGES }}
+        INPUT_NO_STANDARD: ${{ inputs.NO_STANDARD }}
+        INPUT_INSERT_ISSUE_URLS: ${{ inputs.INSERT_ISSUE_URLS }}
+        INPUT_TARGET_REPO: ${{ inputs.TARGET_REPO }}
 branding:
   icon: 'check-square'
   color: 'orange'
@@ -31,15 +66,18 @@ inputs:
   TOKEN:
     description: 'The GitHub access token to allow us to retrieve, create and update issues (automatically set)'
     required: false
-    default: ${{ github.token }}
+    default: '${{ github.token }}'
+  TARGET_REPO:
+    description: "Optional target repository to create issues in (e.g. 'owner/repo'). If not provided, issues will be created in the current repository."
+    required: false
   CLOSE_ISSUES:
     description: 'Optional input specifying whether to attempt to close an issue when a TODO is removed'
     required: false
-    default: true
+    default: 'true'
   AUTO_P:
     description: 'For multiline TODOs, format each line as a new paragraph when creating the issue'
     required: false
-    default: true
+    default: 'true'
   PROJECT:
     description: "User or organization project to link issues to, format 'project_type/owner/project_name'"
     required: false
@@ -52,7 +90,7 @@ inputs:
   AUTO_ASSIGN:
     description: 'Automatically assign new issues to the user who triggered the action'
     required: false
-    default: false
+    default: 'false'
   ACTOR:
     description: 'The username of the person who triggered the action (automatically set)'
     required: false
@@ -74,15 +112,15 @@ inputs:
   ESCAPE:
     description: 'Escape all special Markdown characters'
     required: false
-    default: true
+    default: 'true'
   LANGUAGES:
     description: 'A collection of comma-delimited URLs or local paths for custom language files'
     required: false
   NO_STANDARD:
     description: "Exclude loading the default 'syntax.json' and 'languages.yml' files from the repository"
     required: false
-    default: false
+    default: 'false'
   INSERT_ISSUE_URLS:
     description: 'Whether the action should insert the URL for a newly-created issue into the associated TODO comment'
     required: false
-    default: false
+    default: 'false'