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>

pbs-tools/Cargo.toml

@@ -18,7 +18,7 @@ futures = "0.3"
 hex = "0.4.3"
 lazy_static = "1.4"
 libc = "0.2"
-log = "0.4"
+log = "0.4.17"
 nix = "0.19.1"
 nom = "5.1"
 openssl = "0.10"