fix: mime.getType is not a function in CJS build (#416)

[MrRefactoring]

Problem

When using jira.js v5.x with CommonJS (require('jira.js')), calling issueAttachments.addAttachment() fails with:

TypeError: mime.getType is not a function

The library depended on mime@^4.1.0, which is ESM-only; require('mime') in the CJS bundle does not expose .getType().

Solution

• Replaced mime with mime-types, which works in both ESM and CJS.
• Use mimeTypes.lookup(filename) directly in version2/issueAttachments, version3/issueAttachments, and serviceDesk/serviceDesk for MIME type detection.

Changes

• Removed mime dependency; added mime-types and @types/mime-types.
• Version bump to 5.3.1.
• CHANGELOG entry for mime.getType is not a function in v5.x when using CommonJS #416.

Closes #416

[MrRefactoring]

Hi everyone 👋

I've published a dev tag with this fix so it can be tested before merging/release.

You can install and try it using:
jira.js@5.3.1-dev20260219071444

Please let me know if everything works as expected or if you notice any issues. Thanks!