This update for seamonkey fixes the following issues:

update to SeaMonkey 2.53.13

* Updates to devtools.
* Updates to build configuration.
* Starting the switch from Python 2 to Python 3 in the build system.
* Removal of array comprehensions, legacy iterators and generators
bug 1414340 and bug 1098412.
* Adding initial optional chaining and Promise.allSettled() support.
* SeaMonkey 2.53.13 uses the same backend as Firefox and contains
the relevant Firefox 60.8 security fixes.
* SeaMonkey 2.53.13 shares most parts of the mail and news code with
Thunderbird. Please read the Thunderbird 60.8.0 release notes for
specific security fixes in this release.
* Additional important security fixes up to Current Firefox 91.11
and Thunderbird 91.11 ESR plus many enhancements have been
backported. We will continue to enhance SeaMonkey security in
subsequent 2.53.x beta and release versions as fast as we are able
to.