This reverts commitc1826eb.

Implement Default for CompactFormatter

Add Clone and Debug impls to map iterators

Older versions produce slightly differently normalized outputwhen run against 1.90.0+ Rust compiler.

Raise required compiler to Rust 1.61

Switch serde dependency to serde_core

    warning: variables can be used directly in the `format!` string       --> src/ser.rs:448:15        |    448 |         match write!(adapter, "{}", value) {        |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^        |        = help: for further information visithttps://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args        = note: `-W clippy::uninlined-format-args` implied by `-W clippy::pedantic`        = help: to override `-W clippy::pedantic` add `#[allow(clippy::uninlined_format_args)]`    help: change this to        |    448 -         match write!(adapter, "{}", value) {    448 +         match write!(adapter, "{value}") {        |    warning: variables can be used directly in the `format!` string       --> src/value/mod.rs:182:37        |    182 |             Value::Bool(boolean) => write!(formatter, "Bool({})", boolean),        |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        |        = help: for further information visithttps://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args    help: change this to        |    182 -             Value::Bool(boolean) => write!(formatter, "Bool({})", boolean),    182 +             Value::Bool(boolean) => write!(formatter, "Bool({boolean})"),        |    warning: variables can be used directly in the `format!` string       --> src/value/mod.rs:184:38        |    184 |             Value::String(string) => write!(formatter, "String({:?})", string),        |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        |        = help: for further information visithttps://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args    help: change this to        |    184 -             Value::String(string) => write!(formatter, "String({:?})", string),    184 +             Value::String(string) => write!(formatter, "String({string:?})"),        |    warning: variables can be used directly in the `format!` string       --> src/number.rs:365:9        |    365 |         write!(formatter, "Number({})", self)        |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        |        = help: for further information visithttps://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args    help: change this to        |    365 -         write!(formatter, "Number({})", self)    365 +         write!(formatter, "Number({self})")        |