Accessing variable in format() method gives an error.

Describe the bug
Accessing variable in format() method gives an error.

To Reproduce
Steps to reproduce the behavior:

1. Write a similar step in GitHub Action job:

   • name: Output variable
     run: |
     my_variable ='blabla'
     echo ${{ format('startOfString{0}', $my_variable ) }}
     shell: bash

2. Run corresponding GitHub Action

3. See error :
   "The workflow is not valid. .github/workflows/my_workflow_file.yml (Line: a, Col: b): Unexpected symbol: '$my_variable'. Located at position... "

Expected behavior
String with substituted value should be printed .

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [Windows]
• Browser [Microsoft Edge]
• Version [131]

Start with the reproduction in .github/workflows/my_workflow_file.yml and review the GitHub Actions expression and shell-variable syntax used in the run block. Determine whether the reported error is handled by this toolkit or by workflow expression evaluation; done means confirming the responsible component and documenting or reproducing the expected substituted output.