Add dependency to SearchAPI module in .info file.

Problem/Motivation

This module relies on the SearchAPI module, but does not define the dependency on the module in the .info file.

Proposed resolution

Add key to define dependency on the SearchAPI module.

Remaining tasks

Add:

dependencies:
  - search_api:search_api

to the module's search_api_block.info.yml file.

User interface changes

N/A

API changes

N/A

Data model changes

N/A