Make an explicit 'fax' feature

Cargo.toml

@@ -20,7 +20,8 @@ exclude = ["tests/images/*", "tests/fuzz_images/*"]
 half = { version = "2.4.1" }
 quick-error = "2.0.1"
 
-fax = { version = "0.2.4", optional = true }
+# Rename to avoid confusion with the feature name.
+fax34 = { package = "fax", version = "0.2.4", optional = true }
 flate2 = { version = "1.0.20", optional = true }
 weezl = { version = "0.1.10", optional = true }
 zstd = { version = "0.13", optional = true }
@@ -36,6 +37,7 @@ default = ["deflate", "jpeg", "lzw"]
 
 # Compression algorithms
 deflate = ["dep:flate2"]
+fax = ["dep:fax34"]
 jpeg = ["dep:zune-jpeg"]
 lzw = ["dep:weezl"]
 zstd = ["dep:zstd"]