chore: bump toolchain from 1.81 to 1.86

[Rhaki]

Description

This PR updates the Rust toolchain version in the rust-toolchain file from 1.81 to 1.86.
The upgrade is required to ensure compatibility with the left-curve/left-curve
crates, which will be imported for implementing blockchain agents for Dango.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 10a453c

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (d2fc4a1) to head (10a453c).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #6915   +/-   ##
=====================================
  Coverage   0.00%       0           
=====================================
  Files          1       0    -1     
  Lines         14       0   -14     
=====================================
+ Misses        14       0   -14     

Components	Coverage Δ
core	∅ <ø> (∅)
hooks	∅ <ø> (∅)
isms	∅ <ø> (∅)
token	∅ <ø> (∅)
middlewares	∅ <ø> (∅)

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[kamiyaa]

LGTM 👍

Ran sealevel E2E locally to make sure new rust version works well with sealevel dependencies