Use Apache ContentType instead of Guava MimeType

[blockvote]

No description provided.

[codecov]

Codecov Report

Merging #2 into master will not change coverage.
The diff coverage is 90%.

@@            Coverage Diff            @@
##             master       #2   +/-   ##
=========================================
  Coverage     76.04%   76.04%           
  Complexity       91       91           
=========================================
  Files            14       14           
  Lines           359      359           
  Branches         49       49           
=========================================
  Hits            273      273           
  Misses           58       58           
  Partials         28       28

Impacted Files	Coverage Δ	Complexity Δ
.../io/moia/router/proto/ProtoSerializationHandler.kt	100% <100%> (ø)	4 <0> (ø)	⬇️
...main/kotlin/io/moia/router/SerializationHandler.kt	71.42% <100%> (ø)	0 <0> (ø)	⬇️
...src/main/kotlin/io/moia/router/RequestPredicate.kt	100% <100%> (ø)	13 <0> (ø)	⬇️
...r/src/main/kotlin/io/moia/router/RequestHandler.kt	90.52% <100%> (ø)	24 <1> (ø)	⬇️
...in/kotlin/io/moia/router/DeserializationHandler.kt	62.5% <66.66%> (ø)	0 <0> (ø)	⬇️

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[mduesterhoeft]

Really nice 👍 thanks you!