Rename base solver of Z3alpha. (#199)

Co-authored-by: Martin Jonáš <[email protected]>

Author: martinjonas

submissions/z3_base.json renamed to submissions/z3alpha-base.json

@@ -1,5 +1,5 @@
 {
-    "name": "Z3-4.15.0",
+    "name": "Z3-alpha-base",
     "contributors": [
         "Nikolaj Bjørner et al."
     ],
@@ -27,4 +27,4 @@
             ]
         }
     ]
-}
+}