AVRO-4024: [Rust] Accept only "Nan", "INF", "-INF", "Infinity" and "-Infinity"

This is what the Java SDK (via Jackson library) supports (#3066).
This is what the C# SDK also would support (#3070)

Signed-off-by: Martin Tzvetanov Grigorov <mgrigorov@apache.org>

Author: martin-g

lang/rust/avro/src/types.rs

@@ -933,10 +933,10 @@ impl Value {
     /// IEEE 754 NaN and infinities are not valid JSON numbers.
     /// So they are represented in JSON as strings.
     fn parse_special_float(value: &str) -> Option<f32> {
-        match value.trim().to_ascii_lowercase().as_str() {
-            "nan" | "+nan" | "-nan" => Some(f32::NAN),
-            "inf" | "+inf" | "infinity" | "+infinity" => Some(f32::INFINITY),
-            "-inf" | "-infinity" => Some(f32::NEG_INFINITY),
+        match value {
+            "NaN" => Some(f32::NAN),
+            "INF" | "Infinity" => Some(f32::INFINITY),
+            "-INF" | "-Infinity" => Some(f32::NEG_INFINITY),
             _ => None,
         }
     }

lang/rust/avro/tests/io.rs

@@ -107,14 +107,14 @@ fn default_value_examples() -> &'static Vec<(&'static str, &'static str, Value)>
             (r#""long""#, "5", Value::Long(5)),
             (r#""float""#, "1.1", Value::Float(1.1)),
             (r#""double""#, "1.1", Value::Double(1.1)),
-            (r#""float""#, r#""  +inf ""#, Value::Float(f32::INFINITY)),
+            (r#""float""#, r#""INF""#, Value::Float(f32::INFINITY)),
             (
                 r#""double""#,
                 r#""-Infinity""#,
                 Value::Double(f64::NEG_INFINITY),
             ),
-            (r#""float""#, r#""-NAN""#, Value::Float(f32::NAN)),
-            (r#""double""#, r#""-NAN""#, Value::Double(f64::NAN)),
+            (r#""float""#, r#""NaN""#, Value::Float(f32::NAN)),
+            (r#""double""#, r#""NaN""#, Value::Double(f64::NAN)),
             (
                 r#"{"type": "fixed", "name": "F", "size": 2}"#,
                 r#""a""#,