Try assert_panic_free crate

[Minoru]

Inspired by #33.

My first try led to:

$ cargo build --release
--->8---- snip --->8----
  = note: ld.lld: error: undefined symbol:

          HEY! ACTUAL ERROR DOWN HERE!!! (sorry for that big mess up there) the compiler was unable to prove that some code passed to assert_panic_free is actually panic-free. Please ensure that optimizations are enabled.
          >>> referenced by assert_panic_free.2d69ec46-cgu.0
          >>>               assert_panic_free-265392d598ef8e2f.assert_panic_free.2d69ec46-cgu.0.rcgu.o:(_$LT$assert_panic_free..NoPanic$u20$as$u20$core..ops..drop..Drop$GT$::drop::h5030cb1ebeeff06d) in archive /home/minoru/src/minoru-fediverse-crawler/target/release/deps/libassert_panic_free-265392d598ef8e2f.rlib
          collect2: error: ld returned 1 exit status