Add 1.18 upgrade handler

[Taztingo]

Description

Adds the upgrade handler for 1.18.

closes: #1755

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #1756 (e94ef04) into main (881cb7a) will decrease coverage by 0.01%.
Report is 1 commits behind head on main.
The diff coverage is 57.14%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1756      +/-   ##
==========================================
- Coverage   72.92%   72.92%   -0.01%     
==========================================
  Files         289      289              
  Lines       42240    42254      +14     
==========================================
+ Hits        30805    30813       +8     
- Misses      10077    10081       +4     
- Partials     1358     1360       +2     

Files	Coverage Δ
app/upgrades.go	64.16% <57.14%> (-0.36%)	⬇️

[iramiller]

Tourmaline, nice.