ci: fix doxygen build in doc CI (#49)

* ci: fix doxygen build in doc CI

Signed-off-by: PragmaTwice <twice@apache.org>

* install libclang-15-dev

Signed-off-by: PragmaTwice <twice@apache.org>

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Signed-off-by: PragmaTwice <twice@apache.org>

feat: switch the default mode to safe_mode (#44)

Fix field iterating in skipper::encode_skip for message_coder (#40)

fix field: add ctor for base type (#33)

message: add merge(message...) (#28)

* message: add merge(message...)

* message: add doc for merge(message...)

message: fold through all fields in a message (#22)

* message: add message::fold

* message: add non-const fold

CI: add windows build for MSVC (#18)

* CI: add macos build

* CI: fix macos label

* CI: fix LLVM version

* CI: force clang to use libstdc++

* CI: add windows build

* CI: fix env vars in pwsh

* CI: fix env vars in pwsh

* CI: fix env vars in pwsh

* test: fix missing header

* CI: try to fix benchmark

* CI: try to fix benchmark

* CI: fix github_env

* test: add missing header

* CI: fix benchmark

* README: support MSVC

CI: temporarily remove Windows & Mac OS build

CI: add Debug into build matrix