ci: add optional metrics installation into the GitHub workflow

Closes #100

Author: oleg-jukovec

.github/workflows/fast_testing.yaml

@@ -24,6 +24,11 @@ jobs:
           - '2.6'
           - '2.7'
           - '2.8'
+        metrics-version:
+          - ''
+          - '0.10.0'
+          - '0.11.0'
+          - '0.13.0'
         coveralls: [false]
         include:
           - tarantool: '2.8'
@@ -50,6 +55,10 @@ jobs:
         run: make deps
         if: steps.cache-rocks.outputs.cache-hit != 'true'
 
+      - name: Install metrics
+        if: matrix.metrics-version != ''
+        run: tarantoolctl rocks install metrics ${{ matrix.metrics-version }}
+
       - run: echo $PWD/.rocks/bin >> $GITHUB_PATH
 
       - run: make check