[a11y]: Reporting Period Ending Drop Down can not be navigated using the keyboard

[lsr-explore]

Why is this issue important?

Keyboard and Screen Reader users would not be able to select a different reporting period

Current State

When user visits ARPA Reporting home page - They are not able to navigate the drop down using keyboard.

Expected State

User should be able to navigate and select one of the items in the drop down list using the keyboard only.

Implementation Plan

Review how the drop down is coded and update so it can be navigated using the keyboard only.

Bootstrap docs for dropdown

Relevant Code Snippets

No response