Update Send Slack notification step to send a custom message

.github/workflows/get-xamarin-versions.yml

@@ -45,10 +45,11 @@ jobs:
 
       - name: Send Slack notification
         run: |
+          $message = "The following versions of '${{ env.TOOL_NAME }}' are available, consider adding them to toolset: ${{ env.TOOL_VERSIONS }}"
           ./get-new-tool-versions/send-slack-notification.ps1 -Url "${{ secrets.SLACK_CHANNEL_URL }}" `
                                                                       -ToolName "${{ env.TOOL_NAME }}" `
-                                                                      -ToolVersion "${{ env.TOOL_VERSIONS }}" `
-                                                                      -ImageUrl "https://avatars.githubusercontent.com/u/790012?s=200&v=4"
+                                                                      -ImageUrl "https://avatars.githubusercontent.com/u/790012?s=200&v=4" `
+                                                                      -Text "$message"
 
   check_build:
     name: Check build for failures 
@@ -61,8 +62,8 @@ jobs:
       - name: Send Slack notification if build fails
         run: |
           $pipelineUrl = "$env:GITHUB_SERVER_URL/$env:GITHUB_REPOSITORY/actions/runs/$env:GITHUB_RUN_ID"
-          $Message = "The build of the '${{ env.TOOL_NAME }}' detection pipeline failed :progress-error:\nLink to the pipeline: $pipelineUrl"
+          $message = "The build of the '${{ env.TOOL_NAME }}' detection pipeline failed :progress-error:\nLink to the pipeline: $pipelineUrl"
           ./get-new-tool-versions/send-slack-notification.ps1 -Url "${{ secrets.SLACK_CHANNEL_URL }}" `
                                                                       -ToolName "${{ env.TOOL_NAME }}" `
-                                                                      -Text "$Message" `
+                                                                      -Text "$message" `
                                                                       -ImageUrl "https://avatars.githubusercontent.com/u/790012?s=200&v=4"