Bump ccxt from 1.56.86 to 1.57.3

Bumps [ccxt](https://github.com/ccxt/ccxt) from 1.56.86 to 1.57.3.
- [Release notes](https://github.com/ccxt/ccxt/releases)
- [Changelog](https://github.com/ccxt/ccxt/blob/master/exchanges.cfg)
- [Commits](ccxt/ccxt@1.56.86...1.57.3)

---
updated-dependencies:
- dependency-name: ccxt
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -2,7 +2,7 @@ numpy==1.21.2
 pandas==1.3.3
 pandas-ta==0.3.14b
 
-ccxt==1.56.86
+ccxt==1.57.3
 # Pin cryptography for now due to rust build errors with piwheels
 cryptography==3.4.8
 aiohttp==3.7.4.post0