annotations: Fix pylint violations

annotations: Fix pylint violations

Fix the following:
R1722: Consider using sys.exit() (consider-using-sys-exit)
C0209: Formatting a regular string which could be a f-string (consider-using-f-string)
W0703: Catching too general exception Exception (broad-except)
W1514: Using open without explicitly specifying an encoding (unspecified-encoding)
C0411: standard import "from signal import signal, SIGPIPE, SIG_DFL" should be placed before "from kconfig.annotations import Annotation, KConfig" (wrong-import-order)

Signed-off-by: Juerg Haefliger <juergh@proton.me>