chore(deps): pin dependencies

[renovate-bot]

This PR contains the following updates:

Package	Type	Update	Change
@types/body-parser	devDependencies	pin	^1.17.0 -> 1.17.0
@types/express	devDependencies	pin	^4.16.1 -> 4.17.0
@types/minimist	devDependencies	pin	^1.2.0 -> 1.2.0
@types/mocha	devDependencies	pin	^5.2.6 -> 5.2.7
@types/node	devDependencies	pin	^11.9.5 -> 11.13.13
@types/on-finished	devDependencies	pin	^2.3.1 -> 2.3.1
@types/supertest	devDependencies	pin	^2.0.8 -> 2.0.8
gts	devDependencies	pin	^1.0.0-0 -> 1.0.0
mocha (source)	devDependencies	pin	^6.0.0 -> 6.1.4
power-assert	devDependencies	pin	^1.6.1 -> 1.6.1
supertest	devDependencies	pin	^3.4.2 -> 3.4.2
typescript (source)	devDependencies	pin	^3.3.3333 -> 3.5.1

📌 Important: Renovate will wait until you have merged this Pin PR before creating any upgrade PRs for the affected packages. Add the preset :preserveSemverRanges your config if you instead don't wish to pin dependencies.

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[grant]

Build looks like it's passing.
Error related to #164

See build:
https://travis-ci.com/github/GoogleCloudPlatform/functions-framework-nodejs/builds/178021894

Related to #161