Bump ccxt from 1.68.20 to 1.70.45

Bumps [ccxt](https://github.com/ccxt/ccxt) from 1.68.20 to 1.70.45.
- [Release notes](https://github.com/ccxt/ccxt/releases)
- [Changelog](https://github.com/ccxt/ccxt/blob/master/exchanges.cfg)
- [Commits](https://github.com/ccxt/ccxt/compare/1.68.20...1.70.45)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -4,7 +4,7 @@ pandas==1.3.5; python_version <= '3.7'
 pandas==1.4.0; python_version > '3.7'
 pandas-ta==0.3.14b
 
-ccxt==1.68.20
+ccxt==1.70.45
 # Pin cryptography for now due to rust build errors with piwheels
 cryptography==36.0.1
 aiohttp==3.8.1