fix: bump tracing library to v14

[ca-scribner]

Fixes canonical/tempo-coordinator-k8s-operator#108

Issue

Fixes canonical/tempo-coordinator-k8s-operator#108

Solution

The new tracing lib automatically removes duplicate packages left over from charm upgrades, preventing the exception raised in canonical/tempo-coordinator-k8s-operator#108. Full detail available in

Context

See tempo fix for more context

Merge after #160

Testing Instructions

juju deploy grafana-agent --revision=134 --channel=latest/stable
juju deploy ubuntu
juju relate grafana-agent ubuntu
# wait for deploy to finish and charm to go to blocked (because it has no target for its metrics)

# Build the updated version of the charm
charmcraft pack  

juju refresh grafana-agent --path ./grafana-agent_ubuntu-22.04-amd64.charm
# charm should refresh and go back to blocked.  It should not go to error

Upgrade Notes

[ca-scribner]

We should only merge this once this tempo pr is merged

[ca-scribner]

Everything is now mergable (assuming it passes CI)