fix: ih_schema.sql to comply with eclipse-edc/IdentityHub#451 (#333)

Fix `ih_schema.sql` to comply with eclipse-edc/IdentityHub#451

deployment/assets/postgres/ih_schema.sql

@@ -57,7 +57,8 @@ CREATE TABLE IF NOT EXISTS keypair_resource
     rotation_duration     BIGINT,                                     -- duration during which this keypair is in a transitional state (rotated, not yet deactivated)
     serialized_public_key VARCHAR             NOT NULL,               -- serialized public key (PEM, JWK,...)
     private_key_alias     VARCHAR             NOT NULL,               -- alias under which the private key is stored in the HSM/Vault
-    state                 INT                 NOT NULL DEFAULT 100    -- KeyPairState
+    state                 INT                 NOT NULL DEFAULT 100,   -- KeyPairState
+    key_context           VARCHAR                                     --the key context, will end up in the VerificationMethod of the DID Document
 );
 
 CREATE TABLE IF NOT EXISTS participant_context