lower the msrv of sap to 1.85.0 (#5)

* use `core::str::from_utf8` instead of unstable `str::from_utf8`

revert when rust-lang/rust#131114 is stable

* remove todo comments and add comments with the rust version

* fix comments and add links

* use feature name in comments

* use `String::from_utf8_lossy` instead of `OsStr::display`

* update comments to add the new way of doing things

* use the proper old way in the comment

Author: imnotpoz

src/lib.rs

@@ -223,7 +223,11 @@ where
                 // however the user
                 // can be as bright as Proxima Centauri
                 // or as dark as Sagittarius A
-                let str_arg = match str::from_utf8(arg) {
+                //
+                // `inherent_str_constructors` is not stabilised yet
+                // https://github.com/rust-lang/rust/issues/131114
+                // use `str::from_utf8(arg)` if you don't care about stable rust
+                let str_arg = match core::str::from_utf8(arg) {
                     Err(_e) => {
                         let err = ParsingError::InvalidString;
                         return Err(err);
@@ -257,7 +261,12 @@ where
             // might not be needed,
             // however i am not sure of the user's
             // eternal glory and shine
-            let str_arg = match str::from_utf8(arg.as_encoded_bytes()) {
+            //
+            // `inherent_str_constructors` is not stabilised yet
+            // https://github.com/rust-lang/rust/issues/131114
+            // use `str::from_utf8(arg.as_encoded_bytes())`
+            // if you don't care about stable rust
+            let str_arg = match core::str::from_utf8(arg.as_encoded_bytes()) {
                 Err(_e) => {
                     let err = ParsingError::InvalidString;
                     return Err(err);
@@ -353,14 +362,20 @@ impl Display for ParsingError {
             Self::InvalidOption { reason, offender } => {
                 let reserve = write!(f, "reason: {reason}");
                 if let Some(sentence) = offender {
-                    return write!(f, " at: {}", sentence.display());
+                    // `os_str_display` is stabilised in 1.87.0
+                    // https://github.com/rust-lang/rust/issues/120048
+                    // use `sentence.display()` if you don't care about rust <1.87.0
+                    return write!(f, " at: {}", String::from_utf8_lossy(sentence.as_bytes()));
                 }
 
                 reserve
             }
 
             Self::UnconsumedValue { value } => {
-                write!(f, "leftover value: {}", value.display())
+                // `os_str_display` is stabilised in 1.87.0
+                // https://github.com/rust-lang/rust/issues/120048
+                // use `value.display()` if you don't care about rust <1.87.0
+                write!(f, "leftover value: {}", String::from_utf8_lossy(value.as_bytes()))
             }
 
             Self::UnexpectedArg {