HTCONDOR-1290: attempt to fix rpm build dependencies

Author: ColeBollig

README.md

@@ -15,7 +15,7 @@ Building
 
 To build the `scitokens-cpp` library, the following dependencies are needed:
 
-   - [jwt-cpp](https://github.com/Thalhammer/jwt-cpp): A header-only C++ library for manipulating
+   - [jwt-cpp] v0.5.0 or later (https://github.com/Thalhammer/jwt-cpp): A header-only C++ library for manipulating
      JWTs.
    - OpenSSL 1.0 or later.
    - `sqlite3`

rpm/scitokens-cpp.spec

@@ -18,7 +18,7 @@ Source0: https://github.com/scitokens/scitokens-cpp/releases/download/v%{version
 # inappropriate to include a "Provides", as jwt-cpp is not provided
 # by this package.
 
-BuildRequires: gcc-c++
+BuildRequires: gcc-c++ >= 5.1
 BuildRequires: make
 BuildRequires: cmake3
 BuildRequires: sqlite-devel