Update Okio dependency

[Nayels]

Steps to reproduce:

Deploy to App Engine Standard -> Create API Context (w/ proxy) -> Application won't start and has the following message.

***************************
APPLICATION FAILED TO START
***************************
Description:
An attempt was made to call a method that does not exist. The attempt was made from the following location:
okhttp3.internal.connection.RealConnection.createTunnel(RealConnection.java:411)

The following method did not exist:

'okio.Buffer okio.BufferedSource.getBuffer()'

The method's class, okio.BufferedSource, is available from the following locations:

jar:file:/srv/application-1.jar!/BOOT-INF/lib/okio-1.13.0.jar!/okio/BufferedSource.class

It was loaded from the following location:

jar:file:/srv/application-1.jar!/BOOT-INF/lib/okio-1.13.0.jar!/
Action:
Correct the classpath of your application so that it contains a single, compatible version of okio.BufferedSource

What should happen:

Bump okio version to 1.17.5 (latest)

compile group: 'com.squareup.okio', name: 'okio', version: '1.17.5.'

What happens:

Application fails to start because getBuffer() does not exist in version 1.13.0 of okio only since 1.16.0

SDK version and environment

• Tested on 0.12.4
• Sandbox
• Production

[angelomelonas]

Hi @Nayels, thank you for raising this issue 🙏 I apologise for the super late response.

We are busy reviewing your pull request and will get back to you soon.

[angelomelonas]

This issue will be resolved here: #131