[CI] Fix lit warning from L0 SDK path

[sarnex]

Fixes this warning

D:\github\_work\llvm\llvm\build-e2e\lit.site.cfg.py:22: SyntaxWarning: invalid escape sequence '\g'
  config.level_zero_libs_dir = "D:\github\level-zero_win-sdk\lib"
D:\github\_work\llvm\llvm\build-e2e\lit.site.cfg.py:23: SyntaxWarning: invalid escape sequence '\g'
  config.level_zero_include = "D:\github\level-zero_win-sdk\include"

Tests using the L0 SDK such as SYCL :: Adapters/interop-level-zero.cpp passed, so it seems this didn't break anything.