[DO NOT MERGE] Add pgTap test for amendment chain view

[vrajmohan]

Install pgTap using https://pgtap.org/documentation.html.

Run the tests using pg_prove --verbose -d fectest tests/sql/efiling_amendment_chain.sql

[codecov-io]

Codecov Report

Merging #3268 into develop will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3268      +/-   ##
===========================================
+ Coverage    88.12%   88.13%   +0.01%     
===========================================
  Files           75       76       +1     
  Lines         6087     6102      +15     
===========================================
+ Hits          5364     5378      +14     
- Misses         723      724       +1

Impacted Files	Coverage Δ
webservices/partition/__init__.py	100% <0%> (ø)	⬆️
webservices/partition/sched_b.py	92.85% <0%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 721e71d...5dd8212. Read the comment docs.

[lbeaufort]

We've decided to stick with pytest for testing SQL / MV logic. Example: https://github.com/fecgov/openFEC/blob/develop/tests/integration/test_amendment_chain.py#L14