requirements.txt - remove manifest-tool 1.5.2

Author: Moshe Shahar

requirements.txt

@@ -16,7 +16,6 @@ mbed-host-tests>=1.4.4,<2.0
 mbed-greentea>=0.2.24,<2.0
 beautifulsoup4>=4,<=4.6.3
 pyelftools>=0.24,<=0.25
-manifest-tool==1.5.2
 pycryptodome>=3.9.3,<4
 pyusb>=1.0.0,<2.0.0
 hidapi>=0.7.99,<0.8.0;platform_system!="Linux"