lint-000-license-headers: Add src/sbom/TAGS to exception list

Commit 6dac0c54cd makes the linter checking for license headers on all
files from the src directory. Since this TAGS file doesn't have one,
it's causing a linter error and it makes the QA system complain.
However, the TAGS file doesn't need a license header and thus add it to
the exception list.

Usually the build tests detect such issues, but commit 1d7a9debf2,
which introduced that file, was merged independently from the other
commit, which modifies the linter. Also, the patch that is introducing
this file was based on an older commit at which the patch modifying the
linter wasn't merged yet and so this issue was hidden.

Change-Id: I78da3fa70c39b709478a384da8769fc058ca18ce
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66938
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/lint/lint-000-license-headers

@@ -18,6 +18,7 @@ HEADER_EXCLUDED="\
 ^src/lib/gnat/|\
 ^src/lib/lzmadecode.[ch]\$|\
 ^src/lib/stack.c\$|\
+^src/sbom/TAGS|\
 ^src/vendorcode/|\
 ^util/amdtools/example_input/|\
 ^util/cbfstool/lzma/|\