Update thelounge/thelounge Docker tag to v4

This MR contains the following updates:

Package	Type	Update	Change
thelounge/thelounge	final	major	3.3.0-alpine -> 4.3.0-alpine

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Release Notes

thelounge/thelounge-docker (thelounge/thelounge)

v4.3.0

Compare Source

• Bump [thelounge][1] to 4.3.0.
• Upgrade Node.js base images from 12 to LTS.

v4.2.0

Compare Source

• Bump [thelounge][1] to 4.2.0.
• Add support for ARM (ARM64 + ARMv7) images (#​109) by @​klausenbusk

v4.1.0

Compare Source

• Bump [thelounge][1] to 4.1.0.

v4.0.0

Compare Source

• Bump [thelounge][1] to 4.0.0.

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