upgrade pekko and possibly other dependencies

[pjfanning]

Prior to a Pekko HTTP 1.0.2 release (if there is one) - we should upgrade to Pekko 1.0.3 (or later if one exists in the 1.0.x release line).

We should also check if there are any other dependencies where we should do a patch level upgrade. That is, if we use a dependency version like 1.2.3 and there is a 1.2.4 release that fixes a serious issue, we should upgrade.

No point being too proactive, we can look at this when start planning the Pekko HTTP 1.0.2 release.