Use Azure mirrors of Ubuntu .deb repositories in containers.

This reduces the likelihood of spurious CI failures caused by DDoS filters
being triggered by massive numbers of concurrent CI jobs.

Add a comma before ellipsis in constexpr_swap.

gcc 15 complains that the comma is required before vararg ellipsis.

Fixes boostorg#35.

Add a comma before ellipsis in constexpr_swap.

gcc 15 complains that the comma is required before vararg ellipsis.

Fixes boostorg#35.

Add a comma before ellipsis in constexpr_swap.

gcc 15 complains that the comma is required before vararg ellipsis.

Fixes boostorg#35.

Added a missing dependency on Boost.TypeTraits to CMakeLists.txt.

Replaced macos-11 GHA image with 12, 13 and 14 since 11 is being remo…

…ved.

Replaced macos-11 GHA image with 12, 13 and 14 since 11 is being remo…

…ved.

Added clang-17 CI jobs.

Added clang-17 CI jobs.

Remove C++03 CI jobs, use gcc-11 libstdc++ in clang-12 through 15.