parsers: fix accidental MSRV bump

Jonas Schäfer created 2 years ago

The previous code didn't build with 1.78:

```
error[E0716]: temporary value dropped while borrowed
   --> parsers/src/data_forms/validate.rs:394:46
    |
380 |         let value = match self {
    |             ----- borrow later stored here
...
394 |             Datatype::UserDefined(value) => &format!("x:{value}"),
    |                                              ^^^^^^^^^^^^^^^^^^^-
    |                                              |                  |
    |                                              |                  temporary value is freed at the end of this statement
    |                                              creates a temporary value which is freed while still in use
    |
    = note: consider using a `let` binding to create a longer lived value
    = note: this error originates in the macro `format` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0716]: temporary value dropped while borrowed
   --> parsers/src/data_forms/validate.rs:395:51
    |
380 |         let value = match self {
    |             ----- borrow later stored here
...
395 |             Datatype::Other { prefix, value } => &format!("{prefix}:{value}"),
    |                                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^-
    |                                                   |                         |
    |                                                   |                         temporary value is freed at the end of this statement
    |                                                   creates a temporary value which is freed while still in use
    |
    = note: consider using a `let` binding to create a longer lived value
    = note: this error originates in the macro `format` (in Nightly builds, run with -Z macro-backtrace for more info)

For more information about this error, try `rustc --explain E0716`.
```

This seems like a silly reason to pull up the compiler version
requirements, so I fixed it with a trivial modification.

Change summary

parsers/src/data_forms/validate.rs | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

Detailed changes

parsers/src/data_forms/validate.rs

@@ -391,10 +391,10 @@ impl Display for Datatype {
             Datatype::Short => "xs:short",
             Datatype::String => "xs:string",
             Datatype::Time => "xs:time",
-            Datatype::UserDefined(value) => &format!("x:{value}"),
-            Datatype::Other { prefix, value } => &format!("{prefix}:{value}"),
+            Datatype::UserDefined(value) => return write!(f, "x:{value}"),
+            Datatype::Other { prefix, value } => return write!(f, "{prefix}:{value}"),
         };
-        write!(f, "{value}")
+        f.write_str(value)
     }
 }