Fix query parameter substitution regex

[vitusortner]

Resolves #126

[codecov]

Codecov Report

Merging #127 into develop will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           develop     #127   +/-   ##
========================================
  Coverage    72.54%   72.54%           
========================================
  Files           48       48           
  Lines         1326     1326           
========================================
  Hits           962      962           
  Misses         364      364

Impacted Files	Coverage Δ
...enerator/lib/processor/query_method_processor.dart	100% <100%> (ø)	⬆️

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