[librsvg: 1/2] build: Require rust-1.56

[Federico Mena Quintero <federico src gnome org>]

commit 3391fbc6229957c78e6e334441aa00419d610eb5
Author: Matt Turner <mattst88 gmail com>
Date:   Mon Mar 21 13:23:05 2022 -0700

    build: Require rust-1.56
    
    Rust 2021 is stable in v1.56.0.
    
    Fixes: 507d930f ("update to 2021 edition")

 COMPILING.md | 2 +-
 configure.ac | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/COMPILING.md b/COMPILING.md
index 140514bc9..d77c5e770 100644
--- a/COMPILING.md
+++ b/COMPILING.md
@@ -31,7 +31,7 @@ minimum version is listed here; you may use a newer version instead.
 **Compilers:**
 
 * a C compiler and `make` tool; we recommend GNU `make`.
-* rust 1.52 or later
+* rust 1.56 or later
 * cargo
 
 **Mandatory dependencies:**
diff --git a/configure.ac b/configure.ac
index 0bc556125..a4e356a94 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,7 +107,7 @@ AS_IF(test x$RUSTC = xno,
 
 dnl MSRV - Minimum Supported Rust Version
 dnl If you change this, please update COMPILING.md
-MINIMUM_RUST_VER=1.52
+MINIMUM_RUST_VER=1.56
 rust_version=`$RUSTC --version | sed -e 's/^rustc //g'`
 AX_COMPARE_VERSION([$rust_version],[lt],[$MINIMUM_RUST_VER], [
     AC_MSG_ERROR([librsvg needs at least rustc version $MINIMUM_RUST_VER])