build: add deps.slotmap = 1

Cargo.lock

@@ -108,6 +108,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "slotmap"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e1e08e261d0e8f5c43123b7adf3e4ca1690d655377ac93a03b2c9d3e98de1342"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.89"
@@ -125,6 +134,12 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
 
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -156,4 +171,5 @@ dependencies = [
  "bitflags",
  "cfg-if",
  "pretty_assertions",
+ "slotmap",
 ]

Cargo.toml

@@ -23,6 +23,7 @@ test_buffer_small = ["test_buffer"]
 [dependencies]
 atoi = "0.4"
 bitflags = "1"
+slotmap = "1"
 
 [dev-dependencies]
 anyhow = "1"