Upgrade to rusqlite 0.23

Requires bumping the MSRV to 1.40.0 because libsqlite3-sys uses features
introduced in that version. remove_dir_all can similarly be unpinned.

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.39.0
+          toolchain: 1.40.0
           override: true
 
       # cargo fmt does not build the code, and running it in a fresh clone of
@@ -48,7 +48,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.39.0
+          toolchain: 1.40.0
           override: true
       - name: cargo fetch
         uses: actions-rs/cargo@v1

.travis.yml

@@ -1,6 +1,6 @@
 language: rust
 rust:
-  - 1.39.0
+  - 1.40.0
 
 cache: cargo
 

rust-toolchain

@@ -1 +1 @@
-1.39.0
+1.40.0

zcash_client_sqlite/Cargo.toml

@@ -17,14 +17,13 @@ bs58 = { version = "0.3", features = ["check"] }
 ff = { version = "0.6", path = "../ff" }
 pairing = { version = "0.16", path = "../pairing" }
 protobuf = "2"
-rusqlite = { version = "0.20", features = ["bundled"] }
+rusqlite = { version = "0.23", features = ["bundled"] }
 time = "0.1"
 zcash_client_backend = { version = "0.2", path = "../zcash_client_backend" }
 zcash_primitives = { version = "0.2", path = "../zcash_primitives" }
 
 [dev-dependencies]
 rand_core = "0.5.1"
-remove_dir_all = "=0.5.2" # tempfile dependency; 0.5.3 bumped the MSRV
 tempfile = "3"
 zcash_proofs = { version = "0.2", path = "../zcash_proofs" }