scripts: requirements: Bump imgtool to 2.1.0

Updates the minimum version of imgtool to 2.1.0, which is one year
newer than the 2.0.0 release

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

scripts/requirements-extras.txt

@@ -19,7 +19,7 @@ lpc_checksum
 Pillow>=10.0
 
 # can be used to sign a Zephyr application binary for consumption by a bootloader
-imgtool>=2.0.0
+imgtool>=2.1.0
 
 # used by nanopb module to generate sources from .proto files
 grpcio-tools>=1.47.0