Bump github.com/google/go-cmp from 0.5.2 to 0.5.6 (#52)

Bumps [github.com/google/go-cmp](https://github.com/google/go-cmp) from 0.5.2 to 0.5.6.
- [Release notes](https://github.com/google/go-cmp/releases)
- [Commits](google/go-cmp@v0.5.2...v0.5.6)

---
updated-dependencies:
- dependency-name: github.com/google/go-cmp
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

go.mod

@@ -2,4 +2,4 @@ module github.com/google/go-querystring
 
 go 1.10
 
-require github.com/google/go-cmp v0.5.2
+require github.com/google/go-cmp v0.5.6

go.sum

@@ -1,3 +1,4 @@
-github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
-github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=