Pass "darker" to config dump function to get the correct configuration section name

[akaihola]

Next:

• #The config dump section name is now required darkgraylib#61
• #Release 1.3.0 darkgraylib#63

---

darker -vv used to output:

# Effective configuration:

[tool.darkgraylib]
# [...]


# Configuration options which differ from defaults:

[tool.darkgraylib]
# [...]

This patch corrects it to:

# Effective configuration:

[tool.darker]
# [...]


# Configuration options which differ from defaults:

[tool.darker]
# [...]

Darkgraylib 1.3.0 now requires the section name argument, which we are passing in since this PR.