Remove pyenv related code (closes #1078) (#1084)

## Description

Removes `pyenv` related functionality from gef.py and documents it.

See discussion at #1078

docs/deprecated.md

@@ -16,3 +16,8 @@ page aims to track those changes.
 | `windbg` | Moved | [a933a5a](https://github.com/hugsy/gef-extras/commit/a933a5ac43933742d91f4e299eadf05e3e0670be) | [Link](https://github.com/hugsy/gef-extras/blob/main/scripts/windbg.py) | |
 | `is-syscall` | Moved | [3f79fb38](https://github.com/hugsy/gef-extras/commit/3f79fb382aa9052d073698d40237f98982c5d2de) | [Link](https://github.com/hugsy/gef-extras/blob/main/scripts/syscall_args) | |
 | `syscall-args` | Moved | [3f79fb38](https://github.com/hugsy/gef-extras/commit/3f79fb382aa9052d073698d40237f98982c5d2de) | [Link](https://github.com/hugsy/gef-extras/blob/main/scripts/syscall_args) | |
+
+## Removed support for pyenv
+
+Support for [pyenv](https://github.com/pyenv/pyenv) has been removed after `2024.05`, for more
+information see [#1078](https://github.com/hugsy/gef/issues/1078) and [#1062](https://github.com/hugsy/gef/issues/1062).

gef.py

@@ -11479,16 +11479,6 @@ def target_remote_posthook():
  f"(with Python {'.'.join(map(str, PYTHON_MIN_VERSION))} or higher).")
  exit(1)
 
- try:
- pyenv = which("pyenv")
- pyenv_root = gef_pystring(subprocess.check_output([pyenv, "root"]).strip())
- pyenv_version = gef_pystring(subprocess.check_output([pyenv, "version-name"]).strip())
- site_packages_dir = pathlib.Path(pyenv_root) / f"versions/{pyenv_version}/lib/python{pathlib.Path(pyenv_version).stem}/site-packages"
- assert site_packages_dir.is_dir()
- site.addsitedir(str(site_packages_dir.absolute()))
- except FileNotFoundError:
- pass
-
  # When using a Python virtual environment, GDB still loads the system-installed Python
  # so GEF doesn't load site-packages dir from environment
  # In order to fix it, from the shell with venv activated we run the python binary,