Categories dropdown menu issues with latest jquery

**Describe the bug**
Categories dropdown menu doesn't stay open when clicking on it. Instead, on click, it loads the first available category. The reset button within the dropdown menu (x) doesn't work.

It seems to be related to jquery as loading legacy library fixes the problem. Also, when Multi-select Categories are enabled, the dropdown works slightly better (the menu remains open but the behavior is still wonky and the reset button doesn't. work either).

**To Reproduce**
Steps to reproduce the behavior:
1. Set up the categories with Multi-select Categories disabled
2. Go to job listings (on the frontend Jobs page) and try to select a category
3. One category will be automatically selected
4. To see the rest of the categories, you need to press and hold the dropdown menu
5. Reset using the x inside the menu doesn't work

**Screenshots**
Screencast: https://d.pr/v/83S5jq

**Expected behavior**
When clicking on the dropdown menu, the menu stays open. Resetting through x works.

**Isolating the problem (mark completed items with an [x]):**
- [x] I have deactivated other plugins and confirmed this bug occurs when only the WP Job Manager plugin is active.
- [x] This bug happens with a default WordPress theme active.
- [x] I can reproduce this bug consistently using the steps above.

**WordPress Environment**
- WordPress Version: 5.6, 5.7
- WP Job Manager Version: 1.35
- PHP Version: 7.4
- Other important details: Problem is resolved when using legacy jquery library

Mentioned in 3805169-zen

Reproduce the issue on the frontend Jobs page with Multi-select Categories disabled, using the listed WordPress and WP Job Manager versions if available. Trace the category dropdown and reset-button behavior under the current jQuery library, then verify that clicking keeps the menu open, no category is auto-selected, and the x reset control works.

Written by the indexing model from the issue text.