Fix warnings from cargo generate template

[nategraf]

Context:

error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/ecb7a53/templates/rust-starter/host/Cargo.toml:8:16
  |
8 | risc0-zkvm = { {{ risc0_zkvm }} }
  |                ^
  |
error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/ecb7a53/templates/rust-starter/methods/Cargo.toml:7:17
  |
7 | risc0-build = { {{ risc0_build }} }
  |                 ^
  |
error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/ecb7a53/templates/rust-starter/methods/guest/Cargo.toml:2:9
  |
2 | name = {{ guest_package_name }}
  |         ^
  |
    Updating git repository `https://github.com/risc0/risc0`
error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/da5db8b/templates/rust-starter/host/Cargo.toml:8:16
  |
8 | risc0-zkvm = { {{ risc0_zkvm }} }
  |                ^
  |
error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/da5db8b/templates/rust-starter/methods/Cargo.toml:7:17
  |
7 | risc0-build = { {{ risc0_build }} }
  |                 ^
  |
error: invalid inline table
expected `}`
 --> ../../../../../../../home/ubuntu/.cargo/git/checkouts/risc0-7d6ab9951628e5b1/da5db8b/templates/rust-starter/methods/guest/Cargo.toml:2:9
  |
2 | name = {{ guest_package_name }}
  |         ^
  |

[capossele]

using the risc0 deps as a git dependency is what is causing these compiler errors messages, possibly a regression introduced by rust-lang/cargo#13213