Fix invalid exports

[Polarisation]

What was changed

The exports in package.json has been updated to a valid format. They just needed to start with ./

Why?

Using Next.js + TypeScript + Node.js 16, could not build because the exports in package.json were invalid.

> Build error occurred
Error [ERR_INVALID_PACKAGE_TARGET]: Invalid "exports" target "dist/SegmentedControlWithoutStyles.js" defined for './SegmentedControlWithoutStyles' in the package config node_modules/segmented-control/package.json; targets must start with "./"
    at new NodeError (node:internal/errors:363:5)
    at throwInvalidPackageTarget (node:internal/modules/esm/resolve:340:9)
    at resolvePackageTargetString (node:internal/modules/esm/resolve:368:5)
    at resolvePackageTarget (node:internal/modules/esm/resolve:405:12)
    at packageExportsResolve (node:internal/modules/esm/resolve:506:22)
    at resolveExports (node:internal/modules/cjs/loader:478:36)
    at Function.Module._findPath (node:internal/modules/cjs/loader:518:31)
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:927:27)
    at Function.Module._load (node:internal/modules/cjs/loader:774:27)
    at Module.require (node:internal/modules/cjs/loader:1013:19) {
  type: 'Error',
  code: 'ERR_INVALID_PACKAGE_TARGET'

Checklist

2. How was this tested:

Against a private Next.js + TypeScript + Node.js 16 project.

3. Any docs updates needed?

No