Issue selecting detector file

[zjmorgan]

Short description of the changes:

Could not previously open the dialog browser for detector geometry files.

Long description of the changes:

Check list for the pull request

• [ ] I have read the [CONTRIBUTING]
• [ ] I have read the [CODE_OF_CONDUCT]
• [ ] I have added tests for my changes
• [ ] I have updated the documentation accordingly

Check list for the reviewer

• [ ] I have read the [CONTRIBUTING]
• [ ] I have verified the proposed changes
• [ ] best software practices
  • [ ] all internal functions have an underbar, as is python standard
  • [ ] clearly named variables (better to be verbose in variable names)
  • [ ] code comments explaining the intent of code blocks
• [ ] All the tests are passing
• [ ] The documentation is up to date
• [ ] code comments added when explaining intent

Manual test for the reviewer

Install crystalplan and change the detector geometry

References