BB2-4268: Add default fhir-v3 url for running selenium tests locally

[stiwarisemanticbits]

JIRA Ticket:
BB2-4268

What Does This PR Do?

Before this PR selenium tests locally were failing because FHIR_URL_V3=https://invalid_fhir_url_v3.gov.
They were failing because of below error

In this PR we have added FHIR_URL_V3 default value in docker environment variable

What Should Reviewers Watch For?

1. Checkout this branch
2. Export all aws keys from cloud tammer
3. Execute ./docker-compose/run_selenium_tests_local.sh

If you're reviewing this PR, please check for these things in particular:

Validation

What Security Implications Does This PR Have?

Please indicate if this PR does any of the following:

• Adds any new software dependencies
• Modifies any security controls
• Adds new transmission or storage of data
• Any other changes that could possibly affect security?

• Yes, one or more of the above security implications apply. This PR must not be merged without the ISSO or team
  security engineer's approval.

Any Migrations?

• Yes, there are migrations
  • The migrations should be run PRIOR to the code being deployed
  • The migrations should be run AFTER the code is deployed
  • There is a more complicated migration plan (downtime,
    etc)
• No migrations