Remove dependency on org.apache.kafka/kafka_2.11

[gphilipp]

Tested as follows:

Without the dependency

1. commented out the kafka_2.11 dep in the project.clj
2. started a REPL
3. loaded the jackdaw.test.fixtures ns
4. Evaled ((reset-application-fixture {"application.id" "foo" "bootstrap.servers" "dummy"}) (fn [])) at the REPL from that ns, got this expected result:

   Execution error at jackdaw.test.fixtures/reset-application-fixture$fn (form-init9876001671492860525.clj:221).
   You must add a dependency on a kafka distrib which ships the kafka.tools.StreamsResetter tool

With the dependency

1. Started a REPL
2. loaded the jackdaw.test.fixtures ns
3. Evaled ((reset-application-fixture {"application.id" "foo" "bootstrap.servers" "dummy"}) (fn [])) at the REPL from that ns The StreamResetter tool was invoked but threw an exception due to the dummy params.

[codecov[bot]]

Codecov Report

Merging #235 into master will increase coverage by 0.42%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #235      +/-   ##
==========================================
+ Coverage   80.30%   80.72%   +0.42%     
==========================================
  Files          42       41       -1     
  Lines        2660     2506     -154     
  Branches      153      149       -4     
==========================================
- Hits         2136     2023     -113     
+ Misses        371      334      -37     
+ Partials      153      149       -4     

Impacted Files	Coverage Δ
src/jackdaw/serdes/edn2.clj	45.45% <0.00%> (-45.46%)	:arrow_down:

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