cargo: fix build issue
Using ubuntu 20.04, the build was failing with version cargo 0.47/ rustc 1.47. Following this discussion: https://github.com/rust-lang/cargo/issues/9340 it appears that 0.52 is the minimum version.
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Using ubuntu 20.04, the build was failing with version cargo 0.47/ rustc 1.47. Following this discussion: https://github.com/rust-lang/cargo/issues/9340 it appears that 0.52 is the minimum version.