Bump version to 1.26.1 for release (#28502)
### Description
<!-- Describe your changes. -->
Update the version number across the codebase
- VERSION_NUMBER
- onnxruntime/__init__.py
- docs/python/README.rst
- onnxruntime/core/session/onnxruntime_c_api.cc (static_assert)
- js/ packages (common, node, web, react_native): lib/version.ts,
package.json, package-lock.json
- js/node/script/install-metadata-versions.js (nuget metadata version)
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
This is for a Windows ML release that is needed for EP certification.
Co-authored-by: Aditya Rastogi <adityar@ntdev.microsoft.com>
