Builds fail occasionally

[ankon]

For example https://app.travis-ci.com/github/Collaborne/y-prosemirror/builds/243875205

[1/9] prosemirror: doc transformation
Success: doc transformation in 16.22ms
repeat: npm run test -- --filter "\[1/" 
[2/9] prosemirror: empty not sync
Success: empty not sync in 4.6ms
repeat: npm run test -- --filter "\[2/" 
[3/9] prosemirror: repeat generate prosemirror changes2
Success: repeat generate prosemirror changes2 - 3 repititions in 50.21ms (best: 11.48ms, worst: 20.03ms, median: 18.7ms, average: 16.74ms)
repeat: npm run test -- --filter "\[3/" --seed 1229381034
[4/9] prosemirror: repeat generate prosemirror changes3
Success: repeat generate prosemirror changes3 - 5 repititions in 81.39ms (best: 8.54ms, worst: 37.41ms, median: 10.59ms, average: 16.28ms)
repeat: npm run test -- --filter "\[4/" --seed 2025190525
[5/9] prosemirror: repeat generate prosemirror changes30
Success: repeat generate prosemirror changes30 - 1 repititions in 96.43ms (best: 96.43ms, worst: 96.43ms, median: 96.43ms, average: 96.43ms)
repeat: npm run test -- --filter "\[5/" --seed 744498292
[6/9] prosemirror: repeat generate prosemirror changes40
Success: repeat generate prosemirror changes40 - 1 repititions in 134.68ms (best: 134.68ms, worst: 134.68ms, median: 134.68ms, average: 134.68ms)
repeat: npm run test -- --filter "\[6/" --seed 2843088764
[7/9] prosemirror: repeat generate prosemirror changes70
  X Objects have a different number of attributes obj["content"][4]["content"][1]["content"][2]
  TestError: Test Failed
      at fail (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:600:9)
      at _failMessage (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:425:49)
      at _compare (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:488:9)
      at /home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:502:31
      at Array.forEach (<anonymous>)
      at _compare (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:502:9)
      at /home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:494:9
      at Object.forEach (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/object-dcdd6eed.cjs:30:5)
      at _compare (/home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:490:14)
      at /home/travis/build/Collaborne/y-prosemirror/node_modules/lib0/dist/testing.cjs:502:31
Failure: repeat generate prosemirror changes70 in 306.4ms
repeat: npm run test -- --filter "\[7/" --seed 1208254931
[8/9] prosemirror: repeat generate prosemirror changes100
Success: repeat generate prosemirror changes100 - 1 repititions in 329.43ms (best: 329.43ms, worst: 329.43ms, median: 329.43ms, average: 329.43ms)
repeat: npm run test -- --filter "\[8/" --seed 137948779
[9/9] prosemirror: repeat generate prosemirror changes300
Success: repeat generate prosemirror changes300 - 1 repititions in 739.17ms (best: 739.17ms, worst: 739.17ms, median: 739.17ms, average: 739.17ms)
repeat: npm run test -- --filter "\[9/" --seed 1330086033

> 1 test failed

This is an upstream problem, for example see yjs#51 yjs#77 and others. Usually retrying the build helps.