Signed-off-by: dependabot[bot] <support@github.com>

Signed-off-by: dependabot[bot] <support@github.com>

Creating a virtual environment through a symlink that points at just the
interpreter binary left `PythonInfo.system_executable` set to the
unresolved symlink. virtualenv derives the `home` and `base-executable`
keys of `pyvenv.cfg` from this value, so the symlink directory got
recorded as the interpreter home even though it contains no `lib/`. 🐛
Layouts where `home` must locate the base interpreter's stdlib, such as
python-build-standalone, end up with a broken environment
(pypa/virtualenv#3157).

The fix ports the `getpath.realpath` semantics that CPython's `venv`
adopts in python/cpython#115237: only the symlink chain of the final
path component gets followed, one `readlink` hop at a time, and every
hop must `samefile` the fully resolved path so that a `normpath` across
a symlinked directory stops the walk. A symlink to the binary alone now
resolves to the real interpreter, while a fully symlinked interpreter
tree keeps its symlinked `home`. The walk runs on POSIX only, matching
CPython's `HAVE_READLINK` gate, and applies to both the non-venv
`original_executable` branch and the venv `sys._base_executable` branch
of `_fast_get_system_executable`.

Cached interpreter records refresh on upgrade because the cache stores
the `_py_info.py` content hash. The companion virtualenv PR
pypa/virtualenv#3166 bumps the dependency floor and its app-data
`py_info` cache key. Fixes #84.