Upgrade ameba to 1.6.1

[collivier]

The latest crystal versions ask to upgrade ameba
Please see [1] and [2] for more details.

[1] crystal-ameba/ameba#372
[2] crystal-ameba/ameba#373

Description

# crystal --version
Crystal 1.12.2 (2024-05-31)

LLVM: 17.0.6
Default target: x86_64-alpine-linux-musl

[kosstennbl]

Agree, change is long-needed and awaited, but we need to update crystal on our runners to make it (see GH actions)

And about crystal update - it seems that there's a circular dependency for us:
Crystal update requires ameba update and ameba update requires crystal update.
See: #1814 #1811