Merge pull request #1028 from Unidata/v1.5.4rel

prepare for v1.5.4 release

Changelog

@@ -1,4 +1,4 @@
- version 1.5.4 (not yet released)
+ version 1.5.4 (tag v1.5.4rel)
 ==============================
  * fix printing of variable objects for variables that end with the letter 'u'
    (issue #983).
@@ -11,7 +11,7 @@
    default chunk cache sizes before opening a Dataset (issue #1018).
  * replace use of numpy's deprecated tostring() method with tobytes()
    (issue #1023).
- * bump minimal numpy version to 1.9
+ * bump minimal numpy version to 1.9 (first version to have tobytes()).
 
  version 1.5.3 (tag v1.5.3rel)
 ==============================

README.md

@@ -10,6 +10,9 @@
 ## News
 For details on the latest updates, see the [Changelog](https://github.com/Unidata/netcdf4-python/blob/master/Changelog).
 
+07/23/2020: Version [1.5.4](https://pypi.python.org/pypi/netCDF4/1.5.4) released]. Now requires 
+numpy >= 1.9.
+
 10/27/2019: Version [1.5.3](https://pypi.python.org/pypi/netCDF4/1.5.3) released]. Fix for
 [issue #972](https://github.com/Unidata/netcdf4-python/issues/972), plus binary wheels for
 python 3.8.