Vendor dependencies

Let's see how I like this workflow.

vendor/log/Cargo.toml

@@ -0,0 +1,112 @@
+# 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]
+name = "log"
+version = "0.4.17"
+authors = ["The Rust Project Developers"]
+build = "build.rs"
+exclude = ["rfcs/**/*"]
+description = """
+A lightweight logging facade for Rust
+"""
+documentation = "https://docs.rs/log"
+readme = "README.md"
+keywords = ["logging"]
+categories = ["development-tools::debugging"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/rust-lang/log"
+
+[package.metadata.docs.rs]
+features = [
+    "std",
+    "serde",
+    "kv_unstable_std",
+    "kv_unstable_sval",
+    "kv_unstable_serde",
+]
+
+[[test]]
+name = "filters"
+path = "tests/filters.rs"
+harness = false
+
+[[test]]
+name = "macros"
+path = "tests/macros.rs"
+harness = true
+
+[dependencies.cfg-if]
+version = "1.0"
+
+[dependencies.serde]
+version = "1.0"
+optional = true
+default-features = false
+
+[dependencies.sval]
+version = "=1.0.0-alpha.5"
+optional = true
+default-features = false
+
+[dependencies.value-bag]
+version = "=1.0.0-alpha.9"
+optional = true
+default-features = false
+
+[dev-dependencies.rustversion]
+version = "1.0"
+
+[dev-dependencies.serde]
+version = "1.0"
+features = ["derive"]
+
+[dev-dependencies.serde_test]
+version = "1.0"
+
+[dev-dependencies.sval]
+version = "=1.0.0-alpha.5"
+features = ["derive"]
+
+[dev-dependencies.value-bag]
+version = "=1.0.0-alpha.9"
+features = ["test"]
+
+[features]
+kv_unstable = ["value-bag"]
+kv_unstable_serde = [
+    "kv_unstable_std",
+    "value-bag/serde",
+    "serde",
+]
+kv_unstable_std = [
+    "std",
+    "kv_unstable",
+    "value-bag/error",
+]
+kv_unstable_sval = [
+    "kv_unstable",
+    "value-bag/sval",
+    "sval",
+]
+max_level_debug = []
+max_level_error = []
+max_level_info = []
+max_level_off = []
+max_level_trace = []
+max_level_warn = []
+release_max_level_debug = []
+release_max_level_error = []
+release_max_level_info = []
+release_max_level_off = []
+release_max_level_trace = []
+release_max_level_warn = []
+std = []