rustical_xml: Use darling for proc-macro parsing

Cargo.lock

@@ -892,6 +892,41 @@ dependencies = [
  "cipher",
 ]
 
+[[package]]
+name = "darling"
+version = "0.20.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f63b86c8a8826a49b8c21f08a2d07338eec8d900540f8630dc76284be802989"
+dependencies = [
+ "darling_core",
+ "darling_macro",
+]
+
+[[package]]
+name = "darling_core"
+version = "0.20.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "95133861a8032aaea082871032f5815eb9e98cef03fa916ab4500513994df9e5"
+dependencies = [
+ "fnv",
+ "ident_case",
+ "proc-macro2",
+ "quote",
+ "strsim",
+ "syn",
+]
+
+[[package]]
+name = "darling_macro"
+version = "0.20.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d336a2a514f6ccccaa3e09b02d41d35330c07ddf03a62165fcec10bb561c7806"
+dependencies = [
+ "darling_core",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "der"
 version = "0.7.9"
@@ -1482,6 +1517,12 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "ident_case"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
+
 [[package]]
 name = "idna"
 version = "0.5.0"
@@ -2582,7 +2623,6 @@ dependencies = [
 name = "rustical_xml"
 version = "0.1.0"
 dependencies = [
- "heck",
  "quick-xml",
  "thiserror",
  "xml_derive",
@@ -3860,6 +3900,7 @@ dependencies = [
 name = "xml_derive"
 version = "0.1.0"
 dependencies = [
+ "darling",
  "heck",
  "proc-macro2",
  "quote",