Avoid sending install notifications in dry-run mode

src/Composer/Installer.php

@@ -234,11 +234,15 @@ class Installer
                 return $res;
             }
         } catch (\Exception $e) {
-            $this->installationManager->notifyInstalls($this->io);
+            if (!$this->dryRun) {
+                $this->installationManager->notifyInstalls($this->io);
+            }
 
             throw $e;
         }
-        $this->installationManager->notifyInstalls($this->io);
+        if (!$this->dryRun) {
+            $this->installationManager->notifyInstalls($this->io);
+        }
 
         // output suggestions if we're in dev mode
         if ($this->devMode) {