refact(config)!: use toml instead of yaml

serde_yaml is deprecated and archived. We should not depend on that.
Therefore switching to toml.

Fixes #76.

man/pacdef.8

@@ -16,7 +16,7 @@ Each section contains one or more packages that can be installed respective pack
 
 .SH CONFIGURATION
 Configure pacdef in its config file. See
-.BR pacdef.yaml(5).
+.BR pacdef.toml(5).
 
 .SS GROUP FILE SYNTAX
 
@@ -163,5 +163,5 @@ Mostly 'steven-omaha'.
 Contributors under https://github.com/steven-omaha/pacdef/graphs/contributors.
 
 .SH SEE ALSO
-.BR pacdef.yaml(5)
+.BR pacdef.toml(5)