ci: pin MSRV dependencies with cargo update and add instructions in README

Author: notmandatory

.github/workflows/cont_integration.yml

@@ -4,14 +4,11 @@ name: CI
 
 jobs:
 
-  build-test:
+  build-test-stable:
     name: Build and test
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        rust:
-          - 1.65.0 # STABLE
-          - 1.57.0 # MSRV
         features:
           - default
           - electrum,sqlite-db
@@ -32,7 +29,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v2
       - name: Generate cache key
-        run: echo "${{ matrix.rust }} ${{ matrix.features }}" | tee .cache_key
+        run: echo "stable ${{ matrix.features }}" | tee .cache_key
       - name: Cache
         uses: actions/cache@v2
         with:
@@ -44,10 +41,63 @@ jobs:
       - name: Setup Rust Toolchain
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: ${{ matrix.rust }}
+          toolchain: stable
+          profile: minimal
+          override: true
+          components: rustfmt, clippy
+      - name: Build
+        run: cargo build --no-default-features --features repl,${{ matrix.features }} --locked
+      - name: Clippy
+        run: cargo clippy -- -D warnings
+      - name: Test
+        run: cargo test --no-default-features --features repl,${{ matrix.features }}
+
+  # MSRV 1.57.0
+  build-test-msrv:
+    name: Build and test MSRV
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        features:
+          - default
+          - electrum,sqlite-db
+          - electrum,key-value-db
+          - electrum
+          - esplora-ureq,sqlite-db
+          #### DEP ERRORS - esplora-reqwest,sqlite-db
+          - compiler,sqlite-db
+          #- compact_filters,sqlite-db # Compact Filters temporarily disabled
+          - rpc,sqlite-db
+          - reserves,electrum,sqlite-db
+          - electrum,verify,sqlite-db
+          # regtest-* features are experimental and not fully usable
+          #### DEP ERRORS - regtest-bitcoin,sqlite-db
+          #### DEP ERRORS - regtest-electrum,sqlite-db
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Generate cache key
+        run: echo "1.57.0 ${{ matrix.features }}" | tee .cache_key
+      - name: Cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('.cache_key') }}-${{ hashFiles('**/Cargo.toml','**/Cargo.lock') }}
+      - name: Setup Rust Toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.57.0
           profile: minimal
           override: true
           components: rustfmt, clippy
+      - name: Pin Dependencies for MSRV 1.57.0
+        run: |
+          cargo update -p hashlink --precise 0.8.1
+          cargo update -p log --precise 0.4.18
       - name: Build
         run: cargo build --no-default-features --features repl,${{ matrix.features }} --locked
       - name: Clippy