Bump version to 20.0.0-rc1 (#1085)

### What
Bump version to 20.0.0-rc1, creating release branch.

### Why
Triggered by @sisuresh in
https://github.com/stellar/rs-soroban-sdk/actions/runs/6154859047.

### What is next

See the release instructions for a full rundown on the release process:
https://github.com/stellar/actions/blob/main/README-rust-release.md

Commit any changes to the `release/v20.0.0-rc1` branch that are needed
in this release.

If this is a regular release releasing from `main`, merge this PR when
ready, and after merging, create a release for this version by going to
this link:
https://github.com/stellar/rs-soroban-sdk/releases/new?tag=v20.0.0-rc1&title=20.0.0-rc1

If this is a backport or patch release of a past version, see the
release instructions. When ready to release this branch create a release
by going to this link:

https://github.com/stellar/rs-soroban-sdk/releases/new?tag=v20.0.0-rc1&title=20.0.0-rc1&target=release/v20.0.0-rc1

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Siddharth Suresh <[email protected]>

Cargo.toml

@@ -29,40 +29,40 @@ members = [
 ]
 
 [workspace.package]
-version = "0.9.2"
+version = "20.0.0-rc1"
 
 [workspace.dependencies]
-soroban-sdk = { version = "0.9.2", path = "soroban-sdk" }
-soroban-sdk-macros = { version = "0.9.2", path = "soroban-sdk-macros" }
-soroban-spec = { version = "0.9.2", path = "soroban-spec" }
-soroban-spec-rust = { version = "0.9.2", path = "soroban-spec-rust" }
-soroban-ledger-snapshot = { version = "0.9.2", path = "soroban-ledger-snapshot" }
-soroban-token-sdk = { version = "0.9.2", path = "soroban-token-sdk" }
+soroban-sdk = { version = "20.0.0-rc1", path = "soroban-sdk" }
+soroban-sdk-macros = { version = "20.0.0-rc1", path = "soroban-sdk-macros" }
+soroban-spec = { version = "20.0.0-rc1", path = "soroban-spec" }
+soroban-spec-rust = { version = "20.0.0-rc1", path = "soroban-spec-rust" }
+soroban-ledger-snapshot = { version = "20.0.0-rc1", path = "soroban-ledger-snapshot" }
+soroban-token-sdk = { version = "20.0.0-rc1", path = "soroban-token-sdk" }
 
 [workspace.dependencies.soroban-env-common]
-version = "0.0.17"
+version = "20.0.0-rc1"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "66a3c504387da5bb5bb0b1cc4b0beb22c74fb252"
+rev = "f19ef13363a1e0cbff7b100c0599a1d63dea88a6"
 
 [workspace.dependencies.soroban-env-guest]
-version = "0.0.17"
+version = "20.0.0-rc1"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "66a3c504387da5bb5bb0b1cc4b0beb22c74fb252"
+rev = "f19ef13363a1e0cbff7b100c0599a1d63dea88a6"
 
 [workspace.dependencies.soroban-env-host]
-version = "0.0.17"
+version = "20.0.0-rc1"
 git = "https://github.com/stellar/rs-soroban-env"
-rev = "66a3c504387da5bb5bb0b1cc4b0beb22c74fb252"
+rev = "f19ef13363a1e0cbff7b100c0599a1d63dea88a6"
 
 [workspace.dependencies.stellar-strkey]
 version = "0.0.7"
 git = "https://github.com/stellar/rs-stellar-strkey"
 rev = "e6ba45c60c16de28c7522586b80ed0150157df73"
 
 [workspace.dependencies.stellar-xdr]
-version = "0.0.17"
+version = "20.0.0-rc1"
 git = "https://github.com/stellar/rs-stellar-xdr"
-rev = "84d4d01f739b4f2c3f445f41bc7464a5621ba58c"
+rev = "d5ce0c9e7aa83461773a6e81662067f35d39e4c1"
 default-features = false
 features = ["curr"]
 

soroban-sdk/src/deploy.rs

@@ -31,7 +31,7 @@
 //! #     let env = Env::default();
 //! #     let contract_address = env.register_contract(None, Contract);
 //! #     // Install the contract code before deploying its instance.
-//! #     let mock_wasm = [0u8; 100];
+//! #     let mock_wasm = [0u8; 0];
 //! #     let wasm_hash = env.deployer().upload_contract_wasm(mock_wasm.as_slice());
 //! #     ContractClient::new(&env, &contract_address).f(&wasm_hash);
 //! # }

soroban-sdk/src/env.rs

@@ -524,7 +524,7 @@ impl Env {
         };
 
         env.ledger().set(internal::LedgerInfo {
-            protocol_version: 0,
+            protocol_version: 20,
             sequence_number: 0,
             timestamp: 0,
             network_id: [0; 32],