tbb@2020_U3: add to this tap and use in gazebo11

[scpeters]

The tbb@2020 formula is deprecated in homebrew-core, which causes brew doctor warnings, so add it to this tap without the deprecation warning.

• https://build.osrfoundation.org/job/gazebo-install-one_liner-homebrew-amd64/2059/

+ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  tbb@2020

[scpeters]

build bottle

[j-rivero]

build bottle

we might need to build bottles for tbb first, and update gazebo afterwards-

[scpeters]

oddly enough, the problem was an upper case character in the formula filename. I created the formula with brew extract and since the formula's version had an uppercase character, it put the invalid uppercase character in the filename. I've proposed a fix for brew extract to avoid this in the future in Homebrew/brew#11440 and have renamed the formula file in c1debbb

[scpeters]

build bottle