Upgrade: jwa dependency from 1.1.5 -> 1.1.6

[andygout]

Upgrades the jwa dependency from ^1.1.5 to ^1.1.6 so that projects not downloading packages on a semver basis (i.e. using a package-lock.json) are able to benefit from the changes introduced in v1.1.6 of that package, namely:

• Dispensing with its dependency of base64url.
• Upgrading ecdsa-sig-formatter from v1.0.9 to v1.0.10, the latter of which dispenses with its dependency of base64url.

Vulnerabilities have been reported (by Whitesource and Synk) in base64url < v3.0.0 and so we would like those versions to be excluded from our dependency tree.

[lgodmer]

Thanks @andygout!
@omsmith can we get a released version with this change? We are also hitting issues in snyk due to the jwa dependency.

[charlenetshos]

@omsmith @brianloveswords we are failing nsp check in one of our projects because of https://nodesecurity.io/advisories/658.
When will this change be released?

[iamariffikri]

Can we have this merged? Node security is bugging us for Out-of-bounds Read in base64url.

[tperamaki]

@brianloveswords I approved this PR, now you can merge it 😃