sysutils/fswatch-mon: Update to 1.13.0

• Update to 1.13.0
  • Changelogs:
    • https://github.com/emcrisostomo/fswatch/releases/tag/1.11.3
    • https://github.com/emcrisostomo/fswatch/releases/tag/1.12.0
    • https://github.com/emcrisostomo/fswatch/releases/tag/1.13.0
• Do not use GH_* variables as USE_GITHUB is not set
• Use DISTVERSION instead of PORTVERSION
• Set LICENSE_FILE
• Fix the order of variables
• Use INSTALL_TARGET=install-strip instead of STRIP_CMD in post-install
• Remove trailing whitespace from pkg-descr

PR: 232556
Reviewed by: krion, mat
Approved by: krion (mentor), mat (mentor), maintainer (timeout)
Differential Revision: https://reviews.freebsd.org/D17666