fix: fix multiple timezones selected simultaenously

[peter-abah]

Description

Fix multiple timezones being selected simultaenously on Language & Region settings page of the Admin Dashboard.

Closes #1211

Changes proposed

What were you told to do?

On the Language & Region settings page of the Admin Dashboard, when the user attempts to select a single time zone from the dropdown, multiple entries are selected at the same time. This behavior makes it impossible for users to choose the correct time zone, leading to potential errors in saving changes.

Requirements:

• Ensure that only one time zone can be selected at any given time.
• Ensure proper selection and deselection behavior in the dropdown.
  Expected Outcome:
• Only the selected time zone should be highlighted, with no other entries selected.

What did you do?

• Change value of timezones used in Select component to be unique
• sorted the timezones

Check List (Check all the applicable boxes)

🚨Please review the contribution guideline for this repository.

• My code follows the code style of this project.
• This PR does not contain plagiarized content.
• The title and description of the PR is clear and explains the approach.
• I am making a pull request against the dev branch (left side).
• My commit messages styles matches our requested structure.
• My code additions will fail neither code linting checks nor unit test.
• I am only making changes to files I was requested to.

Screenshots/Videos

Before

After

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	14.69%	785 / 5341
🔵	Statements	14.37%	787 / 5474
🔵	Functions	14.17%	215 / 1517
🔵	Branches	10.02%	230 / 2294

File Coverage

No changed files found.

Generated in workflow #400

[billmal071]

LGTM