Fix bullet-point lists in release notes

source/releasenotes/3.0.0.rst

source/releasenotes/3.0.1.rst

source/releasenotes/3.0.2.rst

source/releasenotes/3.0.3.rst

source/releasenotes/3.0.4.rst

source/releasenotes/3.0.5.rst

source/releasenotes/3.0.6.rst

source/releasenotes/3.1.0-beta.1.rst

source/releasenotes/3.1.0-beta.2.rst

source/releasenotes/3.1.0-rc.1.rst

source/releasenotes/3.1.0-rc.2.rst

source/releasenotes/3.1.0-rc.3.rst

source/releasenotes/3.1.0.rst

source/releasenotes/3.2.0.rst