build(deps): bump proc-macro2 from 1.0.1 to 1.0.6

Bumps [proc-macro2](https://github.com/alexcrichton/proc-macro2) from 1.0.1 to 1.0.6.
- [Release notes](https://github.com/alexcrichton/proc-macro2/releases)
- [Commits](https://github.com/alexcrichton/proc-macro2/compare/1.0.1...1.0.6)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Cargo.lock

@@ -260,7 +260,7 @@ name = "failure_derive"
 version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -795,7 +795,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.1"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -832,7 +832,7 @@ name = "quote"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1125,7 +1125,7 @@ name = "serde_derive"
 version = "1.0.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1174,7 +1174,7 @@ name = "syn"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1184,7 +1184,7 @@ name = "synstructure"
 version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1642,7 +1642,7 @@ dependencies = [
 "checksum pin-utils 0.1.0-alpha.4 (registry+https://github.com/rust-lang/crates.io-index)" = "5894c618ce612a3fa23881b152b608bafb8c56cfc22f434a3ba3120b40f7b587"
 "checksum pkg-config 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)" = "72d5370d90f49f70bd033c3d75e87fc529fbfff9d6f7cccef07d6170079d91ea"
 "checksum ppv-lite86 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e3cbf9f658cdb5000fcf6f362b8ea2ba154b9f146a61c7a20d647034c6b6561b"
-"checksum proc-macro2 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4c5c2380ae88876faae57698be9e9775e3544decad214599c3a6266cca6ac802"
+"checksum proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "9c9e470a8dc4aeae2dee2f335e8f533e2d4b347e1434e5671afc49b054592f27"
 "checksum publicsuffix 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9bf259a81de2b2eb9850ec990ec78e6a25319715584fd7652b9b26f96fcb1510"
 "checksum pulldown-cmark 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "eef52fac62d0ea7b9b4dc7da092aa64ea7ec3d90af6679422d3d7e0e14b6ee15"
 "checksum quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9274b940887ce9addde99c4eee6b5c44cc494b182b97e73dc8ffdcb3397fd3f0"