e2e: Match notary server version with the main Dockerfile

notary server version 0.5.0 is linux/amd64 only.
Also, e2e stage from top level Dockerfile uses 0.6.1 notary version -
change the Dockerfiles in e2e/testdata to have the same version.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

e2e/testdata/Dockerfile.evil-notary-server

@@ -1,4 +1,4 @@
-ARG NOTARY_VERSION=0.5.0
+ARG NOTARY_VERSION=0.6.1
 FROM notary:server-${NOTARY_VERSION}
 
 COPY ./notary-evil/ /fixtures/

e2e/testdata/Dockerfile.notary-server

@@ -1,4 +1,4 @@
-ARG NOTARY_VERSION=0.5.0
+ARG NOTARY_VERSION=0.6.1
 FROM notary:server-${NOTARY_VERSION}
 
 COPY ./notary/ /fixtures/