Add noexcept to _utils C-equiv functions (#641)

* Add `noexcept` to `_utils` C-equiv functions

The functions in `_utils` are effectively straight C functions. In
Cython 0.x, these would have been treated as `noexcept` by default.
However in Cython 3.x all functions are treated as potentially raising
exceptions (including these). While that is a sensible default in
general, these functions still won't raise exceptions. So tidy things up
by adding `noexcept` to turn off the additional Cython checks emitted in
and around them.

* Swap order of `nogil` & `noexcept`

Fixes a Cython warning when using the opposite ordering.

* style: pre-commit fixes

---------

Co-authored-by: David Stansby <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/release.rst

@@ -16,6 +16,10 @@ Fixes
 * Cleanup ``crc32c`` soft dependency.
   By :user:`John Kirkham <jakirkham>`, :issue:`637`
 
+Improvements
+~~~~~~~~~~~~
+* Add `noexcept` to `_utils` C-equiv functions
+  By :user:`John Kirkham <jakirkham>`, :issue:`641`.
 
 .. _release_0.14.0:
 

numcodecs/_utils.pxd

@@ -8,14 +8,14 @@
 from libc.stdint cimport uint8_t, uint32_t
 
 
-cdef inline void store_le32(uint8_t c[4], uint32_t i) nogil:
+cdef inline void store_le32(uint8_t c[4], uint32_t i) noexcept nogil:
     c[0] = i & 0xFF
     c[1] = (i >> 8) & 0xFF
     c[2] = (i >> 16) & 0xFF
     c[3] = (i >> 24) & 0xFF
 
 
-cdef inline uint32_t load_le32(const uint8_t c[4]) nogil:
+cdef inline uint32_t load_le32(const uint8_t c[4]) noexcept nogil:
     return (
         c[0] |
         (c[1] << 8) |