fix(examples): add firebase as a dependency to complete/simple example

[dzoba]

Description

If you attempt to run the simple example, you will get this error:

It's pretty easily solved by the change in this PR.

Check List

If not relevant to pull request, check off as complete

• [x] All tests passing
• [x] Docs updated with any changes or examples if applicable
• [x] Added tests to ensure new feature(s) work properly

Relevant Issues

Not applicable. I didn't file an issue for this. Let me know if there needs to be one.

[codecov[bot]]

Codecov Report

Merging #866 into master will not change coverage by %. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #866   +/-   ##
=======================================
  Coverage   88.76%   88.76%           
=======================================
  Files          29       29           
  Lines         783      783           
=======================================
  Hits          695      695           
  Misses         88       88           

[dzoba]

Looks like there are issues beyond this, since Todos won't come in and can't be added. If you happen to know a quick fix, that would be helpful

[prescottprue]

After adding the Firebase sdk I am seeing the todos load and can add one. I'll add support for the database emulator so we can see if it maybe has to do with the project itself