feat(bridge): alert error through pagerduty

[moreal]

This resolves #96.

[codecov]

Codecov Report

Merging #98 (21f0a0e) into main (f0ba916) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #98      +/-   ##
==========================================
+ Coverage   94.93%   95.00%   +0.06%     
==========================================
  Files          18       18              
  Lines         316      320       +4     
  Branches       43       43              
==========================================
+ Hits          300      304       +4     
  Misses         10       10              
  Partials        6        6              

Impacted Files	Coverage Δ
bridge/src/observers/burn-event-observer.ts	100.00% <100.00%> (ø)
bridge/src/observers/nine-chronicles.ts	94.87% <100.00%> (+0.13%)	⬆️