ESPHome Dashboard does not work on Windows 10

### The problem

ESPHome Dashboard does not work correctly with Python 3.8.10 and Python 3.9.6 on Windows 10. The website loads but does not respond to a click. The reason for this is that JavaScript files are delivered with content type "text/plain".

This problem is probably related to a bug in the mimetypes.guess_type function for Python on Windows.

### Which version of ESPHome has the issue?

2021.8.2

### What type of installation are you using?

pip

### Which version of Home Assistant has the issue?

_No response_

### What platform are you using?

ESP8266

### Board

_No response_

### Component causing the issue

_No response_

### Example YAML snippet

_No response_

### Anything in the logs that might be useful for us?

_No response_

### Additional information

_No response_