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-datastore/Cargo.toml

@@ -14,7 +14,7 @@ futures = "0.3"
 hex = { version = "0.4.3", features = [ "serde" ] }
 lazy_static = "1.4"
 libc = "0.2"
-log = "0.4"
+log = "0.4.17"
 nix = "0.19.1"
 openssl = "0.10"
 serde = { version = "1.0", features = ["derive"] }