Revert lossy conversions to use as

The conversions in this changeset cannot use the `From<T>` trait
implementation because the conversion is lossy, either because they
involve converting a signed value to an unsigned value (`i32`⇒`u64`)
or because the convert from a larger data type to a smaller one
(`u64`⇒`i32`). In this case, the `as` type cast is necessary to perform
a bitwise conversion.

This coercion can cause negative values to become very large unsigned
values. This is intentional on line 90.

juniper/src/integrations/serde.rs

@@ -77,7 +77,7 @@ impl<'de> de::Deserialize<'de> for InputValue {
                 E: de::Error,
             {
                 if value >= i64::from(i32::min_value()) && value <= i64::from(i32::max_value()) {
-                    Ok(InputValue::int(i32::from(value)))
+                    Ok(InputValue::int(value as i32))
                 } else {
                     Err(E::custom(format!("integer out of range")))
                 }
@@ -87,8 +87,8 @@ impl<'de> de::Deserialize<'de> for InputValue {
             where
                 E: de::Error,
             {
-                if value <= u64::from(i32::max_value()) {
-                    self.visit_i64(i64::from(value))
+                if value <= i32::max_value() as u64 {
+                    self.visit_i64(value as i64)
                 } else {
                     Err(E::custom(format!("integer out of range")))
                 }