if path contains '#', then image does not render in preview

**Issue**

If a relative path segment contains `#`, then the referenced image does not render in preview.

**Configuration**

* macOS Big Sur 11.6.3
* MacDown: version 0.7.3 (1008.4) and version 0.8.0d71 (1079)

**Test Files**

[test folder.zip](https://github.com/MacDownApp/macdown/files/8064417/test.folder.zip)

**Expected Result**

The expected result is achieved when _the relative paths do not contain `#`_.

```
test folder
├── notes.md
└── notes_files
└── blue.png
```


**Unexpected Results**

See the zip file of a failing test example which is attached in the above **Test Files** section. (The parent path of the relative path does not appear to have this issue in MacDown.)

```
test folder
├── notes#.md
└── notes#_files
└── blue.png
```


Start by extracting the attached test folder.zip and reproducing the preview failure in MacDown using the stated versions and macOS configuration. Trace how the preview resolves relative image paths containing #, then verify that blue.png renders for notes#.md and notes#_files while paths without # continue to work.

Written by the indexing model from the issue text.