chore(deps): update typescript to ^3

[waitingsong]

Checklist

• npm test passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

Description of change

[waitingsong]

https://travis-ci.org/eggjs/egg-bin/jobs/596864701

No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#build-times-out-because-no-output-was-received

这个异常和跑 nodejs_v12 的差不多。

[codecov]

Codecov Report

Merging #144 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #144   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     12           
  Lines         229    229           
=====================================
  Hits          229    229

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[atian25]

ceived in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on

这是 travis 的问题？

[waitingsong]

有可能 travis 不稳定吧。