supporting Hyphen"-" in Compile and Search

Hi,
I tried the below code, where we want to search jmes path having **Hyphen "-"**, I'm getting the following error
**SyntaxError: Unexpected token at the end of the expression: tNumber**

From the code it looks like the **Hyphen "-"** is considered as a reference to get numeric values.
https://github.com/jmespath/go-jmespath/blob/3d4fd11601ddca248480565884e34e393313cd62/lexer.go#L164-L166

```
package main

import (
"encoding/json"
"fmt"
"github.com/jmespath/go-jmespath"
)

func main() {
var jsondata = []byte(`{"foo-bar": {"bar": "car"}}`)
var data interface{}
err := json.Unmarshal(jsondata, &data)
fmt.Println(err)
precompiled, err := jmespath.Compile("foo-bar")
if err != nil{
fmt.Println(err)
}
result, err := precompiled.Search(data)
fmt.Printf("%T", result)
fmt.Println(result, err)
}
```

Is it possible to pass values containing **Hyphen "-"**? `jmespath.Compile("foo-bar")`

**Please let us know if there is any other way to do that, If not please consider our suggestion.**
**Opinion**:-

Can we add a filter func in Lexer
https://github.com/jmespath/go-jmespath/blob/3d4fd11601ddca248480565884e34e393313cd62/lexer.go#L23-L29
```
type SkipFilterFunc func(r rune) bool

// Lexer contains information about the expression being tokenized.
type Lexer struct {
expression string // The expression provided by the user.
currentPos int // The current position in the string.
lastWidth int // The width of the current rune. This
buf bytes.Buffer // Internal buffer used for building up values.
skipFunc []SkipFilterFunc
}
```

https://github.com/jmespath/go-jmespath/blob/3d4fd11601ddca248480565884e34e393313cd62/lexer.go#L388-L392
And we can call those filter func inside consuleUnquotedIdentifier

```
if r < 0 || r > 128 || identifierTrailingBits[uint64(r)/64]&(1<<(uint64(r)%64)) == 0 {
skip := false
for _, skipFunc := range lexer.skipFunc{
if ok := skipFunc(r); ok {
skip = true
break
}
}
if skip{
continue
}
lexer.back()
break

}
```

So I can support any key to be part of string and can override the existing feature.