Added TRUST_X_FORWARDED_HEADERS environment variable

The release of phpipam 1.6 [introduced a new config.php setting](https://github.com/phpipam/phpipam/releases/tag/v1.6.0) called `$trust_x_forwarded_headers`.
This setting is false by default, and breaks integration between this docker image and reverse proxies, as the X_FORWARDED_FOR_* headers are no longer trusted.

Update phpIpam to 1.5.2

Change in Cisco MIB download place

As stated at [SNMP
FAQ](https://www.cisco.com/c/en/us/support/docs/ip/simple-network-management-protocol-snmp/9226-mibs-9226.html#anc4),
Github is a trusted place to fetch MIBs, so using it.

Fix DB customization via envvar (#75)

Since 1.5 version, the DB host config default value changed from "localhost" to "127.0.0.1" [1], so the replacement performed here didn't work anymore.

[1] phpipam/phpipam@2fe6f9a

v1.4.7

Update to 1.4.5

Setup "docker-publish" GitHub Action

Docker Hub stopped the autobuild service hook in June.
We have to move to GH Actions to continue triggering builds when commit occurs.

Update to 1.4.2

php: remove gd-native-ttf option on gd build

Fixes #59

Signed-off-by: pierrecdn <me@pierre-cheynier.net>

Release 1.3.2

Upgrading to phpipam 1.3.2, see https://github.com/phpipam/phpipam/releases/1.3.2