Fix false positives in for_where with pattern matching

[marcelofabri]

Fixes #1968

[SwiftLintBot]

	12 Messages
📖	Linting Aerial with this PR took 0.45s vs 0.39s on master (15% slower)
📖	Linting Alamofire with this PR took 3.42s vs 3.26s on master (4% slower)
📖	Linting Firefox with this PR took 13.11s vs 13.46s on master (2% faster)
📖	Linting Kickstarter with this PR took 20.38s vs 21.07s on master (3% faster)
📖	Linting Moya with this PR took 1.77s vs 1.86s on master (4% faster)
📖	Linting Nimble with this PR took 1.89s vs 1.98s on master (4% faster)
📖	Linting Quick with this PR took 0.55s vs 0.58s on master (5% faster)
📖	Linting Realm with this PR took 3.43s vs 3.61s on master (4% faster)
📖	Linting SourceKitten with this PR took 1.13s vs 1.15s on master (1% faster)
📖	Linting Sourcery with this PR took 4.6s vs 4.75s on master (3% faster)
📖	Linting Swift with this PR took 14.74s vs 14.95s on master (1% faster)
📖	Linting WordPress with this PR took 13.76s vs 13.84s on master (0% faster)

Generated by 🚫 Danger

[codecov-io]

Codecov Report

Merging #1978 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1978   +/-   ##
=======================================
  Coverage   89.62%   89.62%           
=======================================
  Files         246      246           
  Lines       14390    14390           
  Branches      923      923           
=======================================
  Hits        12897    12897           
  Misses       1479     1479           
  Partials       14       14

Impacted Files	Coverage Δ
Source/SwiftLintFramework/Rules/ForWhereRule.swift	94.52% <100%> (ø)	⬆️

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