Fix & Modernize CI: upgrade to RabbitMQ 4.3.0 and bump other deps

[flamble]

When raising #113, I realised we needed to do some CI updates to get the tests passing again and generally modernise some of the testing dependencies.

Integration Dockerfile:

• Upgrade from rabbitmq:3.7.28 (EOL) to 4.3.0
• Replace python3.8 (EOL) with system python3
• Use apt python3-pip instead of curl get-pip.py (fixes PyYAML build)
• Combine apt-get update and install into single RUN layer
• Enable RabbitMQ file logging (4.x defaults to console-only in Docker)
• Disable rabbitmq_prometheus plugin (port conflict with multi-node tests)
• Set NODE_OPTIONS=--dns-result-order=ipv4first (Node 17+ IPv6 fix)

Build system (Conan 1 to Conan 2):

• Use CMakeDeps + CMakeToolchain generators instead of cmake generator
• Replace conanbuildinfo.cmake/conan_basic_setup() with find_package()
• Link explicit Boost component targets instead of CONAN_LIBS
• Simplify bootstrap script (Conan 2 profile handles compiler settings)
• Pass CMAKE_TOOLCHAIN_FILE to cmake via Makefile
• Default CMAKE_BUILD_TYPE to Release for Conan 2 toolchain
• Remove CONAN_BIN_DIRS workaround in authproto (fixed in Conan 2)

Acceptance tests:

• Replace python3.8 with python3 throughout
• Use RABBITMQ_NODENAME=@localhost for predictable log filenames
• Create /tmp/logs before starting RabbitMQ (4.x doesn't auto-create)
• Set RABBITMQ_LOGS explicitly (4.x requires it for file logging)
• Update amqplib/amqp-connection-manager (frame_max >= 8192 for RabbitMQ 4.x)

CI workflow:

• Replace turtlebrowser/get-conan with setup-python + pip install conan
• Update actions/checkout from v2 to v4

[michaelklishin]

FWIW the latest RabbitMQ release is 4.3.1, the latest 4.2 release is 4.2.7.

[flamble]

FWIW the latest RabbitMQ release is 4.3.1, the latest 4.2 release is 4.2.7.

Thanks, that's a good point. I'd agree there's no reason no to use the latest of 4.3.1 here. (I had been testing something else with 4.2.3 which is why I'd picked that).

[flamble]

@michaelklishin - I used 4.3.0 since it doesn't look like 4.3.1 has an image yet. Welcome to bump it up once it does!