Fix python buildenv dockerfile name

[liliankasem]

Issue describing the changes in this PR

resolves #4740

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• I have added all required tests (Unit tests, E2E tests)

Additional information

Tested on Windows:

PS C:\Users\likasem\Desktop\pythonapp313> & $env:FUNC_CLI --version
4.5.0-dev
PS C:\Users\me\Desktop\pythonapp313> & $env:FUNC_CLI pack --build-native-deps
'local.settings.json' found in root directory (C:\Users\me\Desktop\pythonapp313).
Resolving worker runtime to 'python'.
'local.settings.json' found in root directory (C:\Users\me\Desktop\pythonapp313).
Resolving worker runtime to 'python'.

Validating project...

  Validate host.json: PASSED
  Validate Flag Compatibility: PASSED
  Validate Folder Structure: PASSED
  Validation .python_packages directory exists: WARNING
    Directory '.python_packages' not found or is empty.
  Validate Python Programming Model: PASSED

Deleting the old .python_packages directory
Running 'docker build -t azure-functions/python:4-python313-buildenv C:\Users\me\AppData\Local\Temp\4-python313-buildenv'..done
Running 'docker exec -t e5085f chmod +x /python_docker_build.sh'..done
Running 'docker exec -t e5085f /python_docker_build.sh'....done
Running 'docker cp e5085f:"/.python_packages/." "C:\Users\me\Desktop\pythonapp313\.python_packages"'..done
Running 'docker kill e5085f'..done
Creating a new package C:\Users\me\Desktop\pythonapp313\pythonapp313.zip

Tested on OSX:

> $FUNC_CLI -v
4.5.0-dev
> $FUNC_CLI pack --build-native-deps
'local.settings.json' found in root directory (/Users/me/python313app).
Resolving worker runtime to 'python'.
'local.settings.json' found in root directory (/Users/me/python313app).
Resolving worker runtime to 'python'.

Validating project...

  Validate host.json: PASSED
  Validate Flag Compatibility: PASSED
  Validate Folder Structure: PASSED
  Validation .python_packages directory exists: WARNING
    Directory '.python_packages' not found or is empty.
  Validate Python Programming Model: PASSED

Running 'docker build -t azure-functions/python:4-python313-buildenv /var/folders/g4/zmwjmq3j3vq7g9x4yflrrwg40000gn/T/4-python313-buildenv'.....done
Running 'docker exec -t dfdf12 chmod +x /python_docker_build.sh'..done
Running 'docker exec -t dfdf12 /python_docker_build.sh'....done
Running 'docker cp dfdf12:"/.python_packages/." "/Users/me/python313app/.python_packages"'..done
Running 'docker kill dfdf12'..done
Creating a new package /Users/me/python313app/python313app.zip