feat(lib/policy/expressions): add system load average to bot expression inputs (#766)

* feat(lib/policy/expressions): add system load average to bot expression inputs

This lets Anubis dynamically react to system load in order to
increase and decrease the required level of scrutiny. High load? More
scrutiny required. Low load? Less scrutiny required.

* docs: spell system correctly

Signed-off-by: Xe Iaso <me@xeiaso.net>

* Update metadata

check-spelling run (pull_request) for Xe/load-average

Signed-off-by: check-spelling-bot <check-spelling-bot@users.noreply.github.com>
on-behalf-of: @check-spelling <check-spelling-bot@check-spelling.dev>

* fix(default-config): don't enable low load average feature by default

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>
Signed-off-by: check-spelling-bot <check-spelling-bot@users.noreply.github.com>
Signed-off-by: Xe Iaso <xe.iaso@techaro.lol>

.github/actions/spelling/expect.txt

@@ -120,6 +120,7 @@ goland
 gomod
 goodbot
 googlebot
+gopsutil
 govulncheck
 goyaml
 GPG
@@ -193,6 +194,7 @@ Mojeek
 mojeekbot
 mozilla
 nbf
+nepeat
 netsurf
 nginx
 nicksnyder
@@ -259,6 +261,7 @@ Semrush
 Seo
 setsebool
 shellcheck
+shirou
 Sidetrade
 simprint
 sitemap