Bump `package.json` to use `node:^19`

[Ocramius]

Bug Report

As found in #134, we use node:^18 in package.json and node:19 in Dockerfile.

Q	A
Version(s)	1.19.0

NPM happily keeps installing everything with a warning:

 #13 1.580 npm WARN EBADENGINE Unsupported engine {
#13 1.581 npm WARN EBADENGINE   package: undefined,
#13 1.581 npm WARN EBADENGINE   required: { node: '^18' },
#13 1.581 npm WARN EBADENGINE   current: { node: 'v19.0.0', npm: '8.19.2' }
#13 1.582 npm WARN EBADENGINE }

That's why I kept going and released 1.19.0 anyway: for 1.20.0 we should fix the dependency range.

[internalsystemerror]

This should error instead of warn with:

.npmrc

engine-strict=true