refactor(types): prefer using import type

[dai-shi]

Since we have downlevel-dts, we can use import type statement.
This is not a big deal, but it makes the code consistent with that in jotai and valtio.

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 3ba00ca:

Sandbox	Source
React	Configuration
React Typescript	Configuration
React Browserify	Configuration
React Snowpack	Configuration
React Parcel	Configuration

[github-actions]

Size Change: 0 B

Total Size: 29.1 kB

ℹ️ View Unchanged

Filename	Size
dist/context.js	518 B
dist/esm/context.js	464 B
dist/esm/index.js	426 B
dist/esm/middleware.js	2.73 kB
dist/esm/middleware/immer.js	210 B
dist/esm/shallow.js	272 B
dist/esm/vanilla.js	402 B
dist/index.js	670 B
dist/middleware.js	3.24 kB
dist/middleware/immer.js	373 B
dist/shallow.js	318 B
dist/system/context.development.js	589 B
dist/system/context.production.js	393 B
dist/system/index.development.js	602 B
dist/system/index.production.js	394 B
dist/system/middleware.development.js	2.82 kB
dist/system/middleware.production.js	1.75 kB
dist/system/middleware/immer.development.js	292 B
dist/system/middleware/immer.production.js	187 B
dist/system/shallow.development.js	338 B
dist/system/shallow.production.js	253 B
dist/system/vanilla.development.js	471 B
dist/system/vanilla.production.js	285 B
dist/umd/context.development.js	662 B
dist/umd/context.production.js	488 B
dist/umd/index.development.js	816 B
dist/umd/index.production.js	570 B
dist/umd/middleware.development.js	3.35 kB
dist/umd/middleware.production.js	2.06 kB
dist/umd/middleware/immer.development.js	514 B
dist/umd/middleware/immer.production.js	371 B
dist/umd/shallow.development.js	447 B
dist/umd/shallow.production.js	344 B
dist/umd/vanilla.development.js	607 B
dist/umd/vanilla.production.js	390 B
dist/vanilla.js	475 B

_{compressed-size-action}