add explicit void types

Author: TomasVotruba

src/Analyzer/QueryPlanResult.php

@@ -35,7 +35,7 @@ public function getSimulatedQuery(): string
     /**
      * @param self::* $result
      */
-    public function addRow(string $table, string $result)
+    public function addRow(string $table, string $result): void
     {
         $this->result[$table] = $result;
     }

src/QueryReflection/ReflectionCache.php

@@ -101,7 +101,7 @@ public function getSchemaHash()
         return $this->schemaHash;
     }
 
-    public function setSchemaHash(string $hash)
+    public function setSchemaHash(string $hash): void
     {
         $this->cacheIsDirty = true;
         $this->schemaHash = $hash;