Mitigate clippy::collapsible-if nightly vs stable.

Signed-off-by: Jason Volk <jason@zemos.net>

Cargo.toml

@@ -980,6 +980,7 @@ style = { level = "warn", priority = -1 }
 assertions_on_constants = { level = "allow", priority = 1 }
 module_inception = { level = "allow", priority = 1 }
 obfuscated_if_else = { level = "allow", priority = 1 }
+collapsible_if = { level = "allow", priority = 1 }                   # TODO stable v. nightly 05-21-25
 
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 suspicious = { level = "warn", priority = -1 }