Fix 1.48 CI error

README.md

@@ -71,19 +71,13 @@ For more information please see `./CONTRIBUTING.md`.
 
 This library should always compile with any combination of features on **Rust 1.48.0**.
 
-To build with the MSRV you will need to pin `serde` (if you have the feature enabled)
+To build with the MSRV, you will need to use the Cargo-minimal.lock file.  **Note:** the MSRV will not get the latest dependency updates.
 
 ```
-# serde 1.0.157 uses syn 2.0 which requires edition 2021
-cargo update -p serde_json --precise 1.0.99
-cargo update -p serde --precise 1.0.156
-cargo update -p quote --precise 1.0.30
-cargo update -p proc-macro2 --precise 1.0.63
-cargo update -p serde_test --precise 1.0.175
+cp Cargo-minimal.lock Cargo.lock
+cargo build
 ```
 
-The above commands are sourced from `./contrib/test.sh`.
-
 ## External dependencies
 
 We integrate with a few external libraries, most notably `serde`. These

contrib/test.sh

@@ -6,23 +6,13 @@ CRATES="bitcoin hashes internals fuzz"
 DEPS="recent minimal"
 MSRV="1\.48\.0"
 
-# Test pinned versions.
+# Test MSRV.
 if cargo --version | grep ${MSRV}; then
-    cargo update -p serde_json --precise 1.0.99
-    cargo update -p serde --precise 1.0.156
-    cargo update -p quote --precise 1.0.30
-    cargo update -p proc-macro2 --precise 1.0.63
-    cargo update -p serde_test --precise 1.0.175
-    # Have to pin this so we can pin `schemars_derive`
-    cargo update -p schemars --precise 0.8.12
-    # schemars_derive 0.8.13 uses edition 2021
-    cargo update -p schemars_derive --precise 0.8.12
-    # memcrh 2.6.0 uses edition 2021
-    cargo update -p memchr --precise 2.5.0
 
-    cargo update -p bitcoin:0.30.1 --precise 0.30.0
+    # Copy minimum dependencies.
+    cp Cargo-minimal.lock Cargo.lock
 
-    # Build MSRV with pinned versions.
+    # Check MSRV with minimum dependencies.
     cargo check --all-features --all-targets
 fi