Change in generation of random 32 bit floating point variates
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There was bug in the generation of 32 bit floating point values from
the uniform distribution that would result in the least significant
bit of the random variate always being 0.  This has been fixed.

This change affects the variates produced by the `random.Generator`
methods ``random``, ``standard_normal``, ``standard_exponential``, and
``standard_gamma``, but only when the dtype is specified as
``numpy.float32``.

Add release note about the fix for 32 bit float random variates.
DOC: Add release note about the fix for 32 bit float random variates.
