fix: keep the sudo password out of files written as root (0.2.1)

run_command prepended the sudo password to the caller's stdin. A sudo
that does not prompt left it for the command, and fix_snmp's
'cat > snmpd.conf' wrote it as the configuration's first line before
making the file world-readable.

run_command now refuses stdin to a privileged command while a sudo
password is set. fix_snmp stages the configuration in a mktemp file
without privilege, and root installs it next to the target and renames
it over, so nothing root runs follows a symlink.

Closes #8

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "napalm-bsd"
-version = "0.2.0"
+version = "0.2.1"
 description = "NAPALM drivers for FreeBSD and OpenBSD hosts via SSH"
 readme = "README.md"
 requires-python = ">=3.10"