Update version, gemspec, and CHANGELOG for 2.8.7 #293

Job	Run time
profile (2.7, native, ubuntu-20.04)	1m 59s
coverage (2.7, ubuntu-20.04)	31s
profile (2.7, pure, ubuntu-20.04)	1m 55s
test (2.2, ubuntu-20.04, Gemfile)	31s
test (2.3, ubuntu-20.04, Gemfile)	27s
test (2.4, ubuntu-20.04, Gemfile)	32s
test (2.5, ubuntu-20.04, Gemfile)	30s
test (2.6, ubuntu-20.04, Gemfile)	33s
test (2.7, ubuntu-20.04, Gemfile)	34s
test (3.0, ubuntu-20.04, Gemfile)	19s
test (3.1, ubuntu-20.04, Gemfile)	24s
test (3.2, ubuntu-20.04, Gemfile)	20s
test (3.3, ubuntu-20.04, Gemfile)	22s
test (jruby-9.1, ubuntu-20.04, Gemfile)	48s
test (jruby-9.2, ubuntu-20.04, Gemfile)	56s
test (jruby-9.3, ubuntu-20.04, Gemfile)	39s
test (jruby-9.4, ubuntu-20.04, Gemfile)	41s
test (truffleruby-22.1, ubuntu-20.04, Gemfile)	2m 19s
test (truffleruby-22.2, ubuntu-20.04, Gemfile)	2m 22s
test (truffleruby-22.3, ubuntu-20.04, Gemfile)	2m 35s
test (ubuntu-20.04, 2.7, gemfiles/public_suffix_2.rb)	35s
test (ubuntu-20.04, 2.7, gemfiles/public_suffix_3.rb)	32s
test (ubuntu-20.04, 2.7, gemfiles/public_suffix_4.rb)	35s
test (ubuntu-22.04, 3.1)	20s
test (macos-11, 3.1)	1m 55s
test (macos-12, 3.1)	40s
test (windows-2019, 3.1)	2m 18s
test (windows-2022, 3.1)	2m 1s
test (windows-2022, jruby-9.3)	1m 28s
test (ubuntu-20.04, head, Gemfile, true)	16s
test (ubuntu-20.04, jruby-head, Gemfile, true)	38s
test (ubuntu-20.04, truffleruby-head, Gemfile, true)	1m 6s
	31m 41s

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