Allow merge commits

[nick-mobilecoin]

Previously merge commits were disallowed. When using stacked PRs, if
initial PR uses a squash merge, git and github loose the information
associate the initial commits in subsequent PRs as belonging to the
initial PR. This results in github saying there are merge conflicts.
Using merge commits allows github to better keep track of which its are
unique to each PR.

Motivation

[nick-mobilecoin]

Current dependencies on/for this PR:

• main
  • PR Allow merge commits #25 👈

This comment was auto-generated by Graphite.

[github-actions]

❌ Unreviewed dependencies found

Crate	Version	Reviews (N/2)	LoC	Left-Pad Index	Geiger	Flags
lazy_static	1.4.0	0	134	365	8	____
mockall_double	0.3.0	0	217	30	0	____
mockall	0.11.4	0	304	80	0	____
temp-env	0.3.4	0	385	18	0	____
displaydoc	0.2.3	0	409	68	24	____
fluent-asserter	0.1.9	0	737	1	0	____
walkdir	2.3.3	0	792	107	0	____
cargo-emit	0.2.1	0	824	10	0	____
url	2.3.1	0	3639	59	0	____

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@5e652ce). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #25   +/-   ##
=======================================
  Coverage        ?   67.48%           
=======================================
  Files           ?        4           
  Lines           ?     1058           
  Branches        ?        0           
=======================================
  Hits            ?      714           
  Misses          ?      344           
  Partials        ?        0           

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