Equals-Character(=) is classified as invalid path

When using SvelteKit, you may end up with folder names like this:
- routes/
- routes/[segments=mySegments]/index.ts

If index.ts would contain a graphql-tag, `graphql-code-generator` would not be able to read from that file. I have narrowed this issue down to the `=`-Sign in my Path Url. `@graphql-tools/utils` contains a function called `isValidPath`. This function checks if the path contains a forbidden character and if its the case, it says the path is invalid.

Sadly, the equal-character is one of those forbidden characters. I have attached a diff that fixes this issue for us.
[@graphql-tools+utils+8.6.10.txt](https://github.com/dotansimha/graphql-code-generator/files/8966642/%40graphql-tools%2Butils%2B8.6.10.txt)

Apparently, the equal-sign isnt valid in FAT32. Merging our patch would likely hurt users using FAT32 - if anybody still uses that.

It would greatly help us to see this improved as it allows us to write our queries where we consume them, using graphql-tags