Update MSRV in CI to 1.85

In ldk-node's update, it bumped its MSRV to 1.85 so we need to do the
same here.

Author: benthecarman

.github/workflows/build.yml

@@ -9,16 +9,16 @@ jobs:
         platform: [
           ubuntu-latest,
           macos-latest,
-          ]
-        toolchain: 
+        ]
+        toolchain:
           [ stable,
             beta,
-            1.75.0, # MSRV
+            1.85.0, # MSRV, same as ldk-node
           ]
         include:
           - toolchain: stable
             check-fmt: true
-          - toolchain: 1.75.0
+          - toolchain: 1.85.0
             msrv: true
     runs-on: ${{ matrix.platform }}
     steps:
@@ -33,8 +33,8 @@ jobs:
         run: rustup component add rustfmt && cargo fmt --all -- --check
       - name: Pin packages to allow for MSRV
         if: matrix.msrv
-        run: |
-          cargo update -p home --precise "0.5.9" --verbose # home v0.5.11 requires rustc 1.81 or newer
+        run: | # None needed yet
+          echo "No packages need pinning for MSRV ${{ matrix.toolchain }}"
       - name: Build on Rust ${{ matrix.toolchain }}
         run: cargo build --verbose --color always
       - name: Test on Rust ${{ matrix.toolchain }}