Use Stockfish 13

Author: hyperchessbot

README.md

@@ -52,6 +52,8 @@ Discuss Hyper Bot on Discord https://discord.gg/8m3Muay .
 
 Post issues on GitHub https://github.com/hyperchessbot/hyperbot/issues .
 ## Config vars
+**USE_STOCKFISH_13** : set it to 'true' to use Stockfish 13 ( Heroku / Linux only )  
+  
 **KEEP_ALIVE_URL** : set this to the full link of your bot home page ( https://[yourappname].herokuapp.com , where change [yourappname] to your Heroku app name ) if you want your bot to be kept alive from early morning till late night Heroku server time, keeping alive a free Heroku bot for 24/7 is not possible, because a free Heroku account has a monthly quota of 550 hours  
 
 **ALWAYS_ON** : requires paid Heroku account, set it to 'true' to keep the bot alive 24/7, you have to set KEEP_ALIVE_URL to your bot's full home page link for ALWAYS_ON to work ( see also the explanation of KEEP_ALIVE_URL config var )  

server.js

@@ -55,6 +55,8 @@ const { isEnvTrue, formatTime, formatName, SECOND, MINUTE } = require('@easyches
 
 let envKeys = []
 
+const useStockfish13 = isEnvTrue('USE_STOCKFISH_13')
+envKeys.push('USE_STOCKFISH_13')
 const appName = process.env.APP_NAME || "hyperchessbot"
 envKeys.push('APP_NAME')
 const generalTimeout = parseInt(process.env.GENERAL_TIMEOUT || "15")
@@ -233,7 +235,13 @@ const { UciEngine, setLogEngine, AnalyzeJob } = require('@easychessanimations/uc
 
 const LC0_EXE = (require('os').platform() == "win32") ? "lc0goorm/lc0.exe" : "lc0goorm/lc0"
 
-const stockfishPath = useScalachess ? 'stockfish12m' : 'stockfish12'
+let stockfishPath = useScalachess ? 'stockfish12m' : 'stockfish12'
+
+if(useStockfish13){	
+	stockfishPath = useScalachess ? 'stockfish13m' : 'stockfish13'
+
+	console.log(`using Stockfish 13 ( ${stockfishPath} )`)
+}
 
 const enginePath = useLc0 ? LC0_EXE : stockfishPath