python: Allow newer prettytable with newer python

This helps to allow installation of Mbed OS requirements into the same
Python environment as mbed-os-tools or mbed-os.

Author: Patater

requirements.txt

@@ -1,6 +1,7 @@
 colorama==0.3.9
 urllib3[secure]>=1.26.5
-prettytable==0.7.2
+PrettyTable<=1.0.1; python_version < '3.6'
+prettytable>=2.0,<3.0; python_version >= '3.6'
 junit-xml==1.8
 PyYAML>=5.4
 jsonschema==2.6.0

tools/cmake/requirements.txt

@@ -1,4 +1,5 @@
-prettytable==0.7.2
+PrettyTable<=1.0.1; python_version < '3.6'
+prettytable>=2.0,<3.0; python_version >= '3.6'
 future>=0.18.0,<1.0
 jinja2>=2.11.3
 intelhex>=2.3.0,<3.0.0