Release 0.6.0

feat: Update usage of cppcheck

Update usage of cppcheck. Switch to C++20 and remove fixed suppressions.

Closes #89

Release 0.5.0

feat: CI build for GitHub actions

CI build workflow for GitHub actions.

0.4.0: Align HdrHistogram to C version

Refactor hdr package, so that it is more closely aligned to
HdrHistogram_c. The advantage being that upstream bug fixes are easier
to track and integrate into the C++ port.

Statistical functions that depend on iterators have been moved to a
separate file in order to break a cyclic dependency between files.

Improve unit-test coverage has also been improved in this commit.

0.3.0: Close memory mapped file

The mmap() function retains a reference to the file associated with
the file descriptor, so the file can be safely closed once the mapping
has been established.

Signed-off-by: Mark Aylett <mark.aylett@reactivemarkets.com>

0.2.0: Http server and examples

HTTP server components and example program.
These components were originally part of the Swirly Cloud project.
The parser is based on the Node.js parser.

Resolves: #13

0.1.1: GH-11 Add Deb package generation support

Update required CMakeLists boost version
Add Debian package generation.
Running cpack -GDEB yields a debian package:

```
dpkg -I dist/toolbox-cpp-snapshot-x86_64.deb
 new debian package, version 2.0.
 size 8005316 bytes: control archive=2299 bytes.
     274 bytes,    11 lines      control
    5200 bytes,    69 lines      md5sums
 Architecture: amd64
 Depends: boost (>=1.67)
 Description: Toolbox - The Reactive C++ Toolbox
 Homepage: https://www.reactivemarkets.com
 Maintainer: development@reactivemarkets.com
 Package: toolbox-cpp
 Priority: optional
 Section: devel
 Version: snapshot
 Installed-Size: 23438
```

0.1.0: Fix tag release build

CircleCI does not run workflows for tags unless you explicitly specify
tag filters. Additionally, if a job requires any other jobs (directly
or indirectly), you must use regular expressions to specify tag
filters for those jobs.