fix logic error in last commit (#905)

Co-authored-by: Gaby <[email protected]>

Author: wrac4242

src/_multithread.js

@@ -4,10 +4,10 @@ if (cluster.isMaster) {
     const electron = require("electron");
     const ipc = electron.ipcMain;
     const signale = require("signale");
-    const osCPUs = require("os").cpus().length
-    // See #904
     // Also, leave a core available for the renderer process
-    const numCPUs = (osCPUs > 8) ? 7 : osCPUs;
+    const osCPUs = require("os").cpus().length - 1
+    // See #904
+    const numCPUs = (osCPUs > 7) ? 7 : osCPUs;
 
     const si = require("systeminformation");