fkYAML version 0.4.1

* remove redundant string allocations for tag names

* remove redundant string allocations for anchor names

* addressed coverage loss

* updated file header contents in the example source files

* fixed missing build instruction for macro examples

* fixed typos

* extract create_object/destroy_object as utility functions

* refactored external_node_constructor

* added builtin to_node impls for sequence-like types

* ensure cv-qualifiers and references are removed in detecting member types

* added builtin to_node impls for mapping-like types

* cleaned up test codes

* added tests of conversions from compatible types to nodes

* fixed typos in doxygen comments

* add builtin to_node() impls for std::pair & std::tuple

* run amalgamation

* fixed compile errors with older gcc/clang versions

* updated docs & examples

* fixed conversions from an empty tuple to a node

* ensure a sequence node is converted to an empty tuple

#468)

* allow ':' to be adjacent to a mapping value right after a JSON-like key

* added test cases to improve coverage

* fixed comment prefix check in the lexer

* added test cases for comments for the lexer

* separate utf-8 validation based on char bytes by overloads

* refactored line break normalization in iterator_input_adapter for char/char8_t

* refactored line break normalization in file/stream_input_adapter for UTF-8

* updated benchmark results

* fixed segfault if the input stream has no contents

* added test cases for empty inputs

* modified not-maintained code in the input_adapter test source file

* early returns an empty string view if an input is empty

* fixed document marker (--- and ...) detections

* emit error if a document marker is found in a flow collection

* run amalgamation

* fixed examples with misindented document markers

* added a workflow job which checks example builds