Change BC8[45]6BS footprint filters

[chschlue]

Fixes issue #951

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All contributions to the kicad library must follow the KiCad library convention

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
  • A new fitting footprint must be submitted if the library does not yet contain one.
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the Travis automated check scripts - fix any errors as required
• Give a reason behind any intentional library convention rule violation.

[evanshultz]

@chschlue
Thanks for taking on a bug fix with your first contribution here!

We want to go about this a bit differently. Since these are fully-specified parts with a defined package in the datasheet, we will keep the existing default footprint. But the footprint filters can remove all but SOT?363*. That should work.

[chschlue]

@evanshultz like so?

[evanshultz]

Indeed. Thank you!