raise minimum app version to 87

Auditor version 87 was released over a year ago and we dropped support
for the older remote attestation API URLs it uses.

Author: thestinger

app/src/main/java/app/attestation/auditor/AttestationProtocol.java

@@ -244,7 +244,7 @@ class AttestationProtocol {
     private static final byte AUDITOR_APP_VARIANT_PLAY = 1;
     private static final byte AUDITOR_APP_VARIANT_DEBUG = 2;
 
-    private static final int AUDITOR_APP_MINIMUM_VERSION = 73;
+    private static final int AUDITOR_APP_MINIMUM_VERSION = 87;
     private static final int OS_VERSION_MINIMUM = 130000;
     private static final int OS_PATCH_LEVEL_MINIMUM = 202208;
     private static final int VENDOR_PATCH_LEVEL_MINIMUM = 20220805;