added php 7.1 compatibility

composer.json

@@ -6,11 +6,15 @@
         {
             "name": "Sebastian Kehr",
             "email": "kehr@ub.uni-leipzig.de"
+        },
+        {
+            "name": "Gregor Gawol",
+            "email": "gawol@ub.uni-leipzig.de"
         }
     ],
     "require": {
-        "php": ">=5.6.0",
-        "psr/http-client": "dev-php5.3-compat#263f4701",
+        "php": ">=7.1",
+        "psr/http-client": "^1.0",
         "netresearch/jsonmapper": "^1.4",
         "guzzlehttp/psr7": "^1.4"
     },
@@ -26,11 +30,5 @@
         "psr-4": {
             "finc\\WorldCat\\SearchClient\\": "tests/"
         }
-    },
-    "repositories": [
-        {
-            "type": "vcs",
-            "url": "git@git.sc.uni-leipzig.de:ubl/finc/psr-http-client.git"
-        }
-    ]
+    }
 }