Resolve home path in dir env vars

[Gitznik]

• I have added a news fragment under changelog.d/ (if the patch affects the end users)

Summary of changes

Fixes #94. Implemented the original suggestion, which seems to perfectly fix the described problem.

Test plan

Tested by running

export PIPX_BIN_DIR="~/test"
pipx environment

->

Environment variables (set by user):

PIPX_HOME=
PIPX_BIN_DIR=~/test
PIPX_MAN_DIR=
PIPX_SHARED_LIBS=
PIPX_DEFAULT_PYTHON=
USE_EMOJI=

Derived values (computed by pipx):

PIPX_HOME=/home/robert/.local/pipx
PIPX_BIN_DIR=/home/robert/test
PIPX_MAN_DIR=/home/robert/.local/share/man
PIPX_SHARED_LIBS=/home/robert/.local/pipx/shared
PIPX_LOCAL_VENVS=/home/robert/.local/pipx/venvs
PIPX_LOG_DIR=/home/robert/.local/pipx/logs
PIPX_TRASH_DIR=/home/robert/.local/pipx/.trash
PIPX_VENV_CACHEDIR=/home/robert/.local/pipx/.cache
PIPX_DEFAULT_PYTHON=/home/robert/private/code/pipx/.nox/develop-3-12/bin/python
USE_EMOJI=true

[chrysle]

I plead for disabling the review dismissal again.

[Gitznik]

I plead for disabling the review dismissal again.

No strong feelings here. I could've fumbled resolving the conflict I guess but I think that risk is quite small.