Bump phenx/php-svg-lib from 0.5.1 to 0.5.2 in /tests

Bumps [phenx/php-svg-lib](https://github.com/PhenX/php-svg-lib) from 0.5.1 to 0.5.2.
- [Release notes](https://github.com/PhenX/php-svg-lib/releases)
- [Commits](dompdf/php-svg-lib@0.5.1...0.5.2)

---
updated-dependencies:
- dependency-name: phenx/php-svg-lib
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>