Version 1.1.0 (Kokkos implementation)

ADDED

- Add the option to bias the phase space e.g. to create more events in the
  tails of distributions. This can be enabled using the `enhance_function`
  option in the `[phase_space]` settings. Possible values are `Zpt`,
  `Max(Htp2,Zpt2)` and `Max(Htp2,ttpt2)`. Phase-space biasing is currently
  only supported by the `Chili(basic)` phase-space generator.
- Add basic support to use Pepper as a library, with API to calculate matrix
  elements. So far this is a working proof-of-principle, but is not yet
  optimised for speed etc. Later releases will expand on this, e.g. to allow
  using Pepper for on-device training of neural networks etc.
- An HDF5 phase space file reader has been added, this can be enabled by
  specifying the `points_file` option in the `[phase_space]` settings.
- The helicity configuration can now be fixed using the `fixed_helicities`
  option in the `[main]` settings section. This option was previously in the
  `[dev]` section, and not very useful for users because the helicities were
  assigned in an unexpected way. This is not rectified and the option should
  behave as expected.
- More details have been added to the "Getting started" tutorials.
- More details have been added to the "Running Pepper for the first time"
  tutorial (previously called "Create your first event sample").
- Pepper's configuration now prints additional helpful details when it
  fails because Kokkos is not found.

FIXED

- The detection of the LHAPDF package has been improved.
- Compilations and runtime issues when LHAPDF was not found have been fixed.
- Tests can now be run without recalculating colour factors when Pepper
  has not been installed; this is achieved by falling back to the colour factor
  data files in the build directory if they have not been installed yet.
- Fix parsing of process strings that are not purely made of jets.
- Fix compilation error when using CUDA and external Chili in the native
  variant.
- Fix weight handling if phase-space is generated on the host, but the PDF are
  evaluated on the device.
- Fix configuration issue when certain CMake variables ended up being empty.
- Fix phase space compilation if HDF5 is not found.
- Improve finding the right python executable to be used for running tests.
- Fix a CMake check for availability of an MPI library; this might fix CMake
  configuration in situations where MPI is not found (but not explicitly
  disabled).
- Fix configurations on CMake versions before v3.24.
- HighFive headers are not erroneously installed any longer.
- Fix small issues in shell snippets listed in the Getting Started tutorials in
  the manual, and streamline these tutorials.
- Improve portability of finding the Thrust dependency for the "native"
  variant.

CHANGED

- Reduce LHAPDF version requirement from 6.5.4 to 6.5.