Bump MSRV to match dependencies

.github/workflows/oxipng.yml

@@ -164,7 +164,7 @@ jobs:
         uses: Swatinem/rust-cache@v2
 
       - name: Install MSRV Rust toolchain
-        uses: dtolnay/rust-toolchain@1.66.0
+        uses: dtolnay/rust-toolchain@1.74.0
 
       - name: Install nextest
         uses: taiki-e/install-action@nextest

Cargo.toml

@@ -19,7 +19,7 @@ license = "MIT"
 name = "oxipng"
 repository = "https://github.com/shssoichiro/oxipng"
 version = "9.0.0"
-rust-version = "1.66.0"
+rust-version = "1.74.0"
 
 [badges]
 travis-ci = { repository = "shssoichiro/oxipng", branch = "master" }