pkce_dart v1.1.0

• BREAKING: Removed the stripTrailingPadding parameter as padding should always be removed as per the spec. If your code passed stripTrailingPadding: true, you can simply remove this parameter and the behavior won't change. If your code passed stripTrailingPadding: false or didn't pass anything, the behavior will change. This shouldn't be a problem, but feel free to open an issue if it is.
• BREAKING: The length parameter now represents the length of the code verifier before it is base64 encoded, so length: 32 corresponds to a code verifier of length 44 and length: 96 corresponds to a length of 128. The length parameter must be between 32 and 96, inclusive, and I strongly recommend using the default length of 32 suggested by the spec.