[
  "atkmm@2.28",
  "autoconf@2.13",
  "bash-completion@2",
  "cairomm@1.14",
  "clang-format@8",
  "gcc@4.9",
  "gcc@5",
  "gcc@6",
  "gcc@7",
  "gcc@8",
  "gcc@9",
  "glibmm@2.64",
  "gnupg@1.4",
  "libsigc++@2",
  "lua@5.1",
  "numpy@1.16",
  "openssl@1.1",
  "pangomm@2.42",
  "python@3.9"
]

[
  "atkmm@2.28",
  "autoconf@2.13",
  "bash-completion@2",
  "cairomm@1.14",
  "clang-format@8",
  "gcc@4.9",
  "gcc@5",
  "gcc@6",
  "gcc@7",
  "gcc@8",
  "gcc@9",
  "glibmm@2.64",
  "gnupg@1.4",
  "libsigc++@2",
  "libxml++@4",
  "libxml++@5",
  "lua@5.1",
  "numpy@1.16",
  "openssl@1.1",
  "pangomm@2.42",
  "python@3.9"
]

Add libxml++@4 and libxml++@5 to keg only allowlist
Add libxml++@4 and libxml++@5 to keg only allowlist
