test: check pkparse with compressed ec

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
diff --git a/tests/data_files/ec_521_pub.comp.pem b/tests/data_files/ec_521_pub.comp.pem
new file mode 100644
index 0000000..4bb8c2b
--- /dev/null
+++ b/tests/data_files/ec_521_pub.comp.pem
@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFgwEAYHKoZIzj0CAQYFK4EEACMDRAADAB3hQtVPaesDjuS3r508oHc2/Zz3Ges1
+TWmHnufzwTb7D7+fCPhr5foSjsGgUdPmxkPoWtqP+s82Y8JgvSyES29W
+-----END PUBLIC KEY-----