RELEASE_NOTES.md: Update release notes for 0.8.0 #954

Job	Run time
Merge tests 4 (Test repo files)	22s
Merge tests 3 (Windows)	1m 19s
Merge tests 2 (Python 3.8)	44s
Merge tests 1 (native_posix)	2m 57s
Merge tests 2 (Python 3.9)	46s
Merge tests 1 (native_posix with asserts)	2m 23s
Merge tests 2 (Python 3.10)	45s
Merge tests 1 (native_posix_64)	2m 47s
Merge tests 2 (Python 3.11)	44s
Merge tests 1 (native_posix_64 with asserts)	2m 30s
Merge tests 2 (Python 3.12)	46s
Merge tests 1 (mps2_an521)	3m 51s
Merge tests 1 (mps2_an521 with asserts)	3m 32s
Release tests 3 (Python ${{ matrix.python-version }}${{ (((matrix.asserts != '') && ' with asserts') \|\| '') }})	0s
Release tests 1 (Fuzz)	0s
Release tests 2 (Python ${{ matrix.python-version }}${{ (((matrix.asserts != '') && ' with asserts') \|\| '') }})	0s
	23m 26s

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