Use resize() instead of reserve() to allocate vector elements

[ RUN      ] SerializeTest.VerifyTest
/usr/include/c++/13/bits/stl_vector.h:1125: std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](size_type) [with _Tp = unsigned char; _Alloc = std::allocator<unsigned char>; reference = unsigned char&; size_type = long unsigned int]: Assertion '__n < this->size()' failed.

Author: ellert

src/scitokens_internal.cpp

@@ -978,9 +978,9 @@ bool scitokens::Validator::store_public_ec_key(const std::string &issuer,
     auto x_num = BN_num_bytes(x_bignum.get());
     auto y_num = BN_num_bytes(y_bignum.get());
     std::vector<unsigned char> x_bin;
-    x_bin.reserve(x_num);
+    x_bin.resize(x_num);
     std::vector<unsigned char> y_bin;
-    y_bin.reserve(y_num);
+    y_bin.resize(y_num);
     BN_bn2bin(x_bignum.get(), &x_bin[0]);
     BN_bn2bin(y_bignum.get(), &y_bin[0]);
     std::string x_str(reinterpret_cast<char *>(&x_bin[0]), x_num);