build: bump required log version

else logging using "{var}" in format strings doesn't work properly.

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

proxmox-rrd/Cargo.toml

@@ -13,7 +13,7 @@ anyhow = "1.0"
 bitflags = "1.2.1"
 crossbeam-channel = "0.5"
 libc = "0.2"
-log = "0.4"
+log = "0.4.17"
 nix = "0.19.1"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"