chore: bump proc-macro-crate to 2.0.0 in borsh-derive (#256)

* derive: proc-macro-crate 2. Raise MSRV to 1.67

* ci: amend build to avoid bumping msrv to 1.67

---------

Co-authored-by: dj8yf0μl <feepdake27@gmail.com>

.github/workflows/rust.yml

@@ -37,11 +37,12 @@ jobs:
     - name: print rustc version
       run: rustc --version
     # remove this step when MSRV >= 1.67.0
-    - name: downgrade `time`, `toml_datetime` crate to support older Rust toolchain
+    - name: downgrade `toml_edit`, time`, `toml_datetime` crate to support older Rust toolchain
       if: matrix.rust_version == '1.66.0' 
       run: |
-        cargo update -p time --precise 0.3.23
+        cargo update -p toml_edit --precise 0.20.2
         cargo update -p toml_datetime --precise 0.6.3
+        cargo update -p time --precise 0.3.23
     - name: Run tests
       run: ./.github/test.sh
 

borsh-derive/Cargo.toml

@@ -18,7 +18,7 @@ proc-macro = true
 
 [dependencies]
 syn = { version = "2", features = ["full", "fold"] }
-proc-macro-crate = "1"
+proc-macro-crate = "2"
 proc-macro2 = "1"
 quote = "1"
 once_cell = "1.18.0"