Pin version of HighFive for integration tests.

Currently, the software we run integration tests against, uses HighFive
v2. Therefore, we run integration tests against the "master" for v2,
which is called `v2.x`.

Author: 1uc

.github/workflows/integration.yml

@@ -16,7 +16,7 @@ on:
       highfive_branch:
         description: "HighFive branch to test against"
         required: false
-        default: "master"
+        default: "v2.x"
         type: string
 
       libsonata_branch:
@@ -46,7 +46,7 @@ jobs:
 
     - name: Build HighFive
       run: |
-        HIGHFIVE_BRANCH=${HIGHFIVE_BRANCH:-"master"}
+        HIGHFIVE_BRANCH=${HIGHFIVE_BRANCH:-"v2.x"}
 
         git clone https://github.com/BlueBrain/HighFive.git \
           --branch ${HIGHFIVE_BRANCH} --recursive
@@ -73,7 +73,7 @@ jobs:
     - name: Build and Test libsonata
       if: success() || failure()
       run: |
-        HIGHFIVE_BRANCH=${HIGHFIVE_BRANCH:-"master"}
+        HIGHFIVE_BRANCH=${HIGHFIVE_BRANCH:-"v2.x"}
         LIBSONATA_BRANCH=${LIBSONATA_BRANCH:-"master"}
 
         git clone https://github.com/BlueBrain/libsonata.git \