alpine/socat container pinned at old version lacking arm64 platform

[dboreham]

As far as I can see the alpine/socat image used is defined here as version 1.7.3.4-r0
That version is quite old and is only available for the amd64 platform on Docker Hub.
The current version 1.7.4.3-r0 is available for other platforms including the increasingly popular arm64.

Used as-is on an arm64 Linux system, it'll fail like this:

    2022-04-20 21:01:21.044 [pool-1-thread-1 @coroutine#7] ERROR 🐳 [alpine/socat:1.7.3.4-r0] traceId:  spanId:  - Log output from the failed container:
    standard_init_linux.go:228: exec user process caused: exec format error

[dboreham]

Note a workaround is to override the default image for alpine/socat like so:

$ grep socat ~/.testcontainers.properties
socat.container.image=alpine/socat:latest

[kiview]

Fixed by #5280