fix: update peer dependency for @rspack/core v2

[chenjiahan]

Summary

Updates the peer dependency requirements for @rspack/core to pre-release ^2.0.0-0 versions.

[Copilot]

Pull request overview

This PR updates the published peer dependency range for @rspack/core so consumers can use postcss-loader with Rspack v2 pre-releases (and onward), aligning package metadata with the new Rspack major.

Changes:

• Expand @rspack/core peer dependency from 0.x || 1.x to 0.x || ^1.0.0 || ^2.0.0-0
• Propagate the same peer dependency range update into package-lock.json

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated no comments.

File	Description
package.json	Broadens @rspack/core peer dependency range to include v2 pre-releases.
package-lock.json	Keeps lockfile metadata in sync with the updated peer dependency range.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.23%. Comparing base (c984ff4) to head (86bf988).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #717   +/-   ##
=======================================
  Coverage   88.23%   88.23%           
=======================================
  Files           3        3           
  Lines         357      357           
  Branches      118      118           
=======================================
  Hits          315      315           
  Misses         38       38           
  Partials        4        4           

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