ci: upgrade macOS versions in CI workflow to 26 (#7486)

* Update macOS versions in CI workflow

* Update macOS runner version in workflow

* Upgrade conan version

* Upgrade Windows conan version

* implement workaround

* Revert "implement workaround"

This reverts commit 08549a1.

* one more macos workaround attempt

Author: DennisOSRM

.github/workflows/osrm-backend.yml

@@ -51,7 +51,7 @@ jobs:
 
           python3 -m venv .venv
           source .venv/Scripts/Activate
-          python3 -m pip install conan==2.15.1
+          python3 -m pip install conan==2.27.1
           conan profile detect --force
 
           cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_CONAN=ON -DENABLE_NODE_BINDINGS=ON ..
@@ -346,7 +346,7 @@ jobs:
             build_node_package: true
             continue-on-error: true
             node: 24
-            runs-on: macos-15-intel # x86_64
+            runs-on: macos-26-intel # x86_64
             BUILD_TYPE: Release
             CCOMPILER: clang
             CXXCOMPILER: clang++
@@ -357,7 +357,7 @@ jobs:
             build_node_package: true
             continue-on-error: true
             node: 24
-            runs-on: macos-15 # arm64
+            runs-on: macos-26 # arm64
             BUILD_TYPE: Release
             CCOMPILER: clang
             CXXCOMPILER: clang++
@@ -518,8 +518,12 @@ jobs:
           if [[ "${ENABLE_CONAN}" == "ON" ]]; then
             python3 -m venv .venv
             source .venv/bin/activate
-            python3 -m pip install conan==2.15.1
+            python3 -m pip install conan==2.27.1
             conan profile detect --force
+            if [[ "${RUNNER_OS}" == "macOS" ]]; then
+              CONAN_DEFAULT_PROFILE="$(conan profile path default)"
+              perl -0pi -e 's/^compiler\.version=.*/compiler.version=17/m' "${CONAN_DEFAULT_PROFILE}"
+            fi
           fi
 
           ccache --zero-stats