build: ignore stderr from git

This is motivated by the use-case of fetching river through the zig
package manager in order to obtain the river protocols. Currently,
git prints a useless error to stderr in this case.

 build.zig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/build.zig b/build.zig
index 9c03e39..821116e 100644
--- a/build.zig
+++ b/build.zig
@@ -43,7 +43,7 @@ pub fn build(b: *Build) !void {
             const git_describe_long = b.runAllowFail(
                 &.{ "git", "-C", b.build_root.path orelse ".", "describe", "--long" },
                 &ret,
-                .Inherit,
+                .Ignore,
             ) catch break :blk version;
 
             var it = mem.splitSequence(u8, mem.trim(u8, git_describe_long, &std.ascii.whitespace), "-");