[refactor] dead import causing issues on BC 1.68

Author: kares

src/main/java/org/jruby/ext/openssl/impl/PKey.java

@@ -54,7 +54,6 @@
 import java.security.spec.X509EncodedKeySpec;
 import javax.crypto.spec.DHParameterSpec;
 
-import org.bouncycastle.asn1.ASN1Encodable;
 import org.bouncycastle.asn1.ASN1EncodableVector;
 import org.bouncycastle.asn1.ASN1Encoding;
 import org.bouncycastle.asn1.ASN1InputStream;
@@ -63,7 +62,6 @@
 import org.bouncycastle.asn1.ASN1Primitive;
 import org.bouncycastle.asn1.ASN1Sequence;
 import org.bouncycastle.asn1.DERBitString;
-import org.bouncycastle.asn1.DERInteger;
 import org.bouncycastle.asn1.DERNull;
 import org.bouncycastle.asn1.DERSequence;
 import org.bouncycastle.asn1.DLSequence;