(#47)
Co-authored-by: depfu[bot] <23717796+depfu[bot]@users.noreply.github.com>

Fix minor typos (#46)

- based on recommendations of https://piotrmurach.com/articles/writing-a-ruby-gem-specification/

- json was added pre Ruby 2.0 in e50430b177

- including review suggestions from @jgraichen

- https://docs.travis-ci.com/user/reference/overview/#deprecated-virtualization-environments

Update rubocop to version 0.80.0 (#44)

Update rubocop to version 0.79.0 (#43)

Update rubocop to version 0.78.0 (#42)

Update rubocop to version 0.77.0 (#41)

Update rubocop to version 0.76.0 (#40)

Update rubocop to version 0.75.0 (#39)

Update rubocop to version 0.74.0 (#37)

Update rubocop to version 0.73.0 (#36)

Update rubocop to version 0.72.0 (#35)

Update rubocop to version 0.71.0 (#34)

Update rubocop to version 0.70.0 (#33)

Update rubocop to version 0.69.0 (#32)

Update rubocop to version 0.68.0 (#31)

Update rubocop to version 0.66.0 (#29)

Update rubocop to version 0.65.0 (#28)

Update rubocop to version 0.64.0 (#27)

Update rack-tracer to version 0.9.0 (#26)

Update rubocop to version 0.63.0 (#25)

Update opentracing to version 0.5.0 (#24)

Update jaeger-client to version 0.10.0 (#22)

Update rubocop to version 0.62.0 (#23)

Update jaeger-client to version 0.8.0 (#21)

Update jaeger-client to version 0.7.0 (#20)

Update rubocop to version 0.61.1 (#19)

Update rubocop to version 0.60.0 (#18)

Update rubocop to version 0.59.0 (#17)

Since rack-tracer now supports OpenTracing.active_span we should start
using it as well and therefore do not need spanmanager gem anymore.

See: Update rack-tracer to version 0.8.0 (#16)

Update rubocop to version 0.58.0 (#14)

Upgrade jaeger-client to version 0.6.0 (#13)