[BUG] startNewVersion script fails on Windows due to Unix shell syntax

[Soumya-codr]

Describe the bug.

Summary
The startNewVersion npm script fails completely on Windows because it uses Unix-specific environment variable syntax that Windows CMD doesn't understand.

Current Problematic Code
File: package.json (line 13)

```json
`"startNewVersion": "newVersion=$npm_config_new_version node scripts/add-new-version.js"`

Problem

• newVersion=$npm_config_new_version is Unix shell syntax
• Windows CMD doesn't recognize variable=value format
• Results in: 'newVersion' is not recognized as an internal or external command

Error Output

npm run startNewVersion
'newVersion' is not recognized as an internal or external command,
operable program or batch file.

Expected behavior

Steps to Reproduce:

1. Use a Windows machine (Windows 10/11)
2. Clone the repository: git clone https://github.com/asyncapi/spec-json-schemas.git
3. Navigate to directory: cd spec-json-schemas
4. Install dependencies: npm install
5. Try to run the script: npm run startNewVersion --new-version=2.7.0
6. Observe the error

Alternative reproduction:

• Simply run: npm run startNewVersion
• Same error occurs immediately

What happens:
Windows CMD tries to parse the Unix syntax and fails at newVersion= because Windows doesn't understand Unix variable assignment syntax.

Screenshots

How to Reproduce

Steps to Reproduce

1. Use a Windows machine (Windows 10/11)
2. Clone the repository: git clone https://github.com/asyncapi/spec-json-schemas.git
3. Navigate to directory: cd spec-json-schemas
4. Install dependencies: npm install
5. Try to run the script: npm run startNewVersion --new-version=2.7.0
6. Observe the error

Alternative reproduction (without version flag):

1. Simply run: npm run startNewVersion
2. Same error occurs immediately

What happens:

• Windows CMD tries to parse: newVersion=$npm_config_new_version node scripts/add-new-version.js
• Fails at newVersion= because Windows doesn't understand Unix variable assignment syntax
• Script never gets executed

🖥️ Device Information [optional]

• Operating System:
• Browser:
• Browser Version:

👀 Have you checked for similar open issues?

• I checked and didn't find similar issue

🏢 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to work on this issue ?

Yes I am willing to submit a PR!

[github-actions]

Welcome to AsyncAPI. Thanks a lot for reporting your first issue. Please check out our contributors guide and the instructions about a basic recommended setup useful for opening a pull request.
Keep in mind there are also other channels you can use to interact with AsyncAPI community. For more details check out this issue.

[Soumya-codr]

@derberg @char0n @GreenRover
I'd like to work on fixing this issue since I discovered it while exploring the codebase.

Proposed Implementation:

1. Update package.json to use: "startNewVersion": "node scripts/add-new-version.js"
2. Modify scripts/add-new-version.js to handle environment variables cross-platform:

   const inputNewVersion = process.env.npm_config_new_version || process.argv[2];

This solution will maintain backward compatibility while fixing the cross-platform issue.
I can have a PR ready soon if maintainers approve this approach.

Thanks
Soumya Sagar