Add HPKE to algorithmFamiliesEnum (#810)

Fixes #809

HPKE is defined in `schema/cryptography-defs.json` but missing from
`schema/cryptography-defs.schema.json#/definitions/algorithmFamiliesEnum`.
BOM 1.7 validates `cryptoProperties.algorithmProperties.algorithmFamily`
against this enum, so valid HPKE usage fails schema validation.

This PR adds `HPKE` to `algorithmFamiliesEnum` (alphabetically between
`GOST` and `HC`).

Author: stevespringett

schema/cryptography-defs.schema.json

@@ -270,6 +270,7 @@
         "FFDH",
         "Fortuna",
         "GOST",
+        "HPKE",
         "HC",
         "HKDF",
         "HMAC",