fix: use cesrnumber when parsing sn in rotate event

[lenkan]

So it does the same as the "interact" function. See

signify-ts/src/keri/core/eventing.ts

Lines 533 to 537 in fddaff2

	const sner = new CesrNumber({}, sn);
	if (sner.num < 1) {
	throw new Error(`Invalid sn = 0x${sner.numh} for ixn.`);
	}

Closes #220

Also related #138

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 82.76%. Comparing base (651bad6) to head (404c377).

❗ Current head 404c377 differs from pull request most recent head 97e071e. Consider uploading reports for the commit 97e071e to get more accurate results

Files	Patch %	Lines
src/keri/core/eventing.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #257   +/-   ##
=======================================
  Coverage   82.76%   82.76%           
=======================================
  Files          46       46           
  Lines        4218     4218           
  Branches     1053     1029   -24     
=======================================
  Hits         3491     3491           
- Misses        698      722   +24     
+ Partials       29        5   -24     

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[lenkan]

Accidentally deleted the branch on my fork. Did not intend to close the PR.