Update ChangeLog

ChangeLog

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 CHANGES                                                                                       
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+2.2
+---
+
+- Added `TREXIO_AUTO` back end for read-only mode (`r`) in PR #80
+- Added unsafe mode (`u`) to `trexio_open`. When enabled, data can be
+overwritten (using conventional `trexio_write`) and groups can be deleted 
+(using new set of `trexio_delete_[group]` functions). Also added `unsafe` 
+attribute to the `metadata` group to indicate that the file might be 
+inconsistent. See PR #79
+- Added `trexio_info` function (prints basic info about the library) in PR #78
+- Added `trexio_inquire` function (checks validity of TREXIO files) in PR #75
+- Fixed ISO_C_BINDING types in the Fortran API (`trexio_f.f90`) in PR #74 and #77
+- Fixed code generation and some missing dependencies in CMake in PR #74
+- Fixed portability issue with sed on MacOS so that `make python-install` works
+- Clean `docs` folder only in the maintainer mode
+
+2.1
+---
+
+- Automatic maintainer mode in PR #66
+- Optional compilation without HDF5 in PR #67
+- Support for CMake build-system and GNU Guix package management in PR #69
+- Add sparse datasets (e.g. for RDMs and 2e ERIs) in PR #70
+- Add Python API for sparse datasets in PR #71
+- Automate build and upload of CPython wheels in PR #72
+- Documentation: changed ordering of AOs in spherical basis
+
 2.0
 ---