Add additional pins required for MSRV builds

Author: TheBlueMatt

.github/workflows/build.yml

@@ -97,6 +97,7 @@ jobs:
           cd fuzz
           cargo update -p syn --precise "2.0.106" --verbose
           cargo update -p quote --precise "1.0.41" --verbose
+          cargo update -p proc-macro2 --precise "1.0.103" --verbose
           RUSTFLAGS="--cfg=fuzzing --cfg=secp256k1_fuzz --cfg=hashes_fuzz" cargo test --verbose --color always
           cargo clean
       - name: Run fuzzers

ci/check-lint.sh

@@ -11,6 +11,8 @@ RUSTC_MINOR_VERSION=$(rustc --version | awk '{ split($2,a,"."); print a[2] }')
 [ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p syn --precise "2.0.106" --verbose
 # quote 1.0.42 requires rustc 1.68.0
 [ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p quote --precise "1.0.41" --verbose
+# Starting with version 1.0.104, the `proc-macro2` crate has an MSRV of rustc 1.68
+[ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p proc-macro2 --precise "1.0.103" --verbose
 
 RUSTFLAGS='-D warnings' cargo clippy -- \
 	`# We use this for sat groupings` \

ci/ci-tests.sh

@@ -10,6 +10,17 @@ RUSTC_MINOR_VERSION=$(rustc --version | awk '{ split($2,a,"."); print a[2] }')
 [ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p syn --precise "2.0.106" --verbose
 # quote 1.0.42 requires rustc 1.68.0
 [ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p quote --precise "1.0.41" --verbose
+# Starting with version 1.0.104, the `proc-macro2` crate has an MSRV of rustc 1.68
+[ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p proc-macro2 --precise "1.0.103" --verbose
+
+# Starting with version 2.0.107, the `syn` crate has an MSRV of rustc 1.68
+[ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p syn --precise "2.0.106" --verbose
+
+# Starting with version 1.0.42, the `quote` crate has an MSRV of rustc 1.68
+[ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p quote --precise "1.0.41" --verbose
+
+# Starting with version 1.0.104, the `proc-macro2` crate has an MSRV of rustc 1.68
+[ "$RUSTC_MINOR_VERSION" -lt 68 ] && cargo update -p proc-macro2 --precise "1.0.103" --verbose
 
 export RUST_BACKTRACE=1