Preserve repeated spaces in badge text

[puneetdixit200]

Summary

• Preserve consecutive whitespace in badge SVG text nodes by adding xml:space="preserve" only when the rendered text contains repeated whitespace.
• Add a regression test for labels like foo bar, where width calculation already accounts for the spaces but browser SVG rendering collapsed them.

Fixes #6510

Tests

• npm_config_cache=/tmp/shields-6510-npm-cache npx mocha badge-maker/lib/make-badge.spec.js (failed before the renderer change, passed after)
• npm_config_cache=/tmp/shields-6510-npm-cache npx mocha --timeout 10000 "badge-maker/**/*.spec.js"
• npm_config_cache=/tmp/shields-6510-npm-cache npm run check-types:package
• npm_config_cache=/tmp/shields-6510-npm-cache npx prettier --check badge-maker/lib/badge-renderers.js badge-maker/lib/make-badge.spec.js
• npm_config_cache=/tmp/shields-6510-npm-cache npx eslint badge-maker/lib/badge-renderers.js badge-maker/lib/make-badge.spec.js
• git diff --check

[github-actions]

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[PyvesB]

Hello @puneetdixit200 👋🏻 Could you clarify why you're submitting changes authored by @pratyushjaiswal0806-dot?