Vendor dependencies

Let's see how I like this workflow.

vendor/toml/Cargo.toml

@@ -0,0 +1,98 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+rust-version = "1.48.0"
+name = "toml"
+version = "0.5.10"
+authors = ["Alex Crichton <alex@alexcrichton.com>"]
+include = [
+    "src/**/*",
+    "Cargo.toml",
+    "LICENSE*",
+    "README.md",
+    "examples/**/*",
+    "benches/**/*",
+    "tests/**/*",
+]
+description = """
+A native Rust encoder and decoder of TOML-formatted files and streams. Provides
+implementations of the standard Serialize/Deserialize traits for TOML data to
+facilitate deserializing and serializing Rust structures.
+"""
+homepage = "https://github.com/toml-rs/toml"
+documentation = "https://docs.rs/toml"
+readme = "README.md"
+keywords = [
+    "encoding",
+    "toml",
+]
+categories = [
+    "encoding",
+    "parser-implementations",
+    "parsing",
+    "config",
+]
+license = "MIT/Apache-2.0"
+repository = "https://github.com/toml-rs/toml"
+
+[[package.metadata.release.pre-release-replacements]]
+file = "CHANGELOG.md"
+search = "Unreleased"
+replace = "{{version}}"
+min = 1
+
+[[package.metadata.release.pre-release-replacements]]
+file = "CHANGELOG.md"
+search = '\.\.\.HEAD'
+replace = "...{{tag_name}}"
+exactly = 1
+
+[[package.metadata.release.pre-release-replacements]]
+file = "CHANGELOG.md"
+search = "ReleaseDate"
+replace = "{{date}}"
+min = 1
+
+[[package.metadata.release.pre-release-replacements]]
+file = "CHANGELOG.md"
+search = "<!-- next-header -->"
+replace = """
+<!-- next-header -->
+## [Unreleased] - ReleaseDate
+"""
+exactly = 1
+
+[[package.metadata.release.pre-release-replacements]]
+file = "CHANGELOG.md"
+search = "<!-- next-url -->"
+replace = """
+<!-- next-url -->
+[Unreleased]: https://github.com/toml-rs/toml_edit/compare/{{tag_name}}...HEAD"""
+exactly = 1
+
+[dependencies.indexmap]
+version = "1.0"
+optional = true
+
+[dependencies.serde]
+version = "1.0.97"
+
+[dev-dependencies.serde_derive]
+version = "1.0"
+
+[dev-dependencies.serde_json]
+version = "1.0"
+
+[features]
+default = []
+preserve_order = ["indexmap"]