[librsvg] Pin the float-cmp crate to 0.4.0 since it made a breaking change in 0.4.1

[Federico Mena Quintero <federico src gnome org>]

commit c51d2226731c2ca0dc2c9b442cb0213ccab0eec5
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Jun 10 09:58:37 2019 -0500

    Pin the float-cmp crate to 0.4.0 since it made a breaking change in 0.4.1

 rsvg_internals/Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/rsvg_internals/Cargo.toml b/rsvg_internals/Cargo.toml
index 737f9adc..2d11c2e8 100644
--- a/rsvg_internals/Cargo.toml
+++ b/rsvg_internals/Cargo.toml
@@ -25,7 +25,7 @@ cssparser = "0.25.5"
 data-url = "0.1"
 downcast-rs = "^1.0.0"
 encoding = "0.2.33"
-float-cmp = "0.4.0"
+float-cmp = "= 0.4.0"
 gdk-pixbuf = "0.6.0"
 gdk-pixbuf-sys = "0.8.0"
 gio = { version="0.6.0", features=["v2_48"] } # per configure.ac