Fix call_with_config string

[dhilst]

Summary

Closes #_

• [n] y/n | Does it introduce breaking changes?
• [n] y/n | Is it dependent on the specific version of ink or pallet-contracts?

Description

Hi everybody! Following the ink tutorial, I found a problem
with the cargo contract upload command. It returns the below error: at https://use.ink/getting-started/calling-your-contract

After the patch:

The patch is so small that I didn't bother to add a test just for it,

Checklist before requesting a review

• [y] My code follows the style guidelines of this project
• [y] I have added an entry to CHANGELOG.md
• [n/a] I have commented on my code, particularly in hard-to-understand areas
• [n] I have added tests that prove my fix is effective or that my feature works
• [n] Any dependent changes have been merged and published in downstream modules