Merge branch 'update-readme-conan-instructions' into 'master'

Update conan instructions

See merge request !486

README.md

@@ -76,11 +76,12 @@ source /opt/rh/devtoolset-9/enable
 ```
 
 CORSIKA 8 uses the [conan](https://conan.io/) package manager to
-manage our dependencies. If you do not have Conan installed, it can be
+manage our dependencies. Currently, version 1.55.0 or higher is required.
+If you do not have Conan installed, it can be
 installed with:
 
 ``` shell
-pip install --user conan
+pip install --user conan~=1.55.0
 ```
 
 ### Compiling

README.rst

@@ -81,11 +81,12 @@ Also initialize devtools, before building CORSIKA 8:
 
 
 CORSIKA 8 uses the `conan <https://conan.io/>`_ package manager to
-manage our dependencies. If you do not have Conan installed, it can be
+manage our dependencies. Currently, version 1.55.0 or higher is required.
+If you do not have Conan installed, it can be
 installed with:
 ::
-   
-  pip install --user conan
+
+  pip install --user conan~=1.55.0
 
   
 Compiling