Do not upgrade installed packages

Author: certik

.github/workflows/CI.yml

@@ -44,12 +44,12 @@ jobs:
       - name: Install Windows Conda Packages
         if: contains(matrix.os, 'windows')
         shell: bash -e -l {0}
-        run: micromamba install m2-bison=3.0.4 m2-filesystem cmake=3.21.1
+        run: micromamba install --freeze-installed m2-bison=3.0.4 m2-filesystem cmake=3.21.1
 
       - name: Install Linux / macOS Conda Packages
         if: contains(matrix.os, 'ubuntu') || contains(matrix.os, 'macos')
         shell: bash -e -l {0}
-        run: micromamba install bison=3.4 nodejs=18 xeus=1.0.1 nlohmann_json=3.9.1
+        run: micromamba install --freeze-installed bison=3.4 nodejs=18
 
 #      - name: Conda info
 #        shell: bash -e -l {0}