serve_file: add headers

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

Cargo.lock

@@ -295,6 +295,16 @@ version = "0.3.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6877bb514081ee2a7ff5ef9de3281f14a4dd4bceac4c09388074a6b5df8a139a"
 
+[[package]]
+name = "mime_guess"
+version = "2.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7c44f8e672c00fe5308fa235f821cb4198414e1c77935c1ab6948d3fd78550e"
+dependencies = [
+ "mime",
+ "unicase",
+]
+
 [[package]]
 name = "mio"
 version = "1.1.0"
@@ -661,6 +671,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "unicase"
+version = "2.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75b844d17643ee918803943289730bec8aac480150456169e647ed0b576ba539"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.22"
@@ -789,6 +805,7 @@ version = "0.1.0"
 dependencies = [
  "axum",
  "futures-util",
+ "mime_guess",
  "rand",
  "tokio",
  "tokio-util",