update version number to start with the letter v

Author: greg7mdp

CMakeLists.txt

@@ -8,7 +8,7 @@
     FetchContent_Declare(
         parallel-hashmap
         GIT_REPOSITORY https://github.com/greg7mdp/parallel-hashmap.git
-        GIT_TAG        1.3.8 # adjust tag/branch/commit as needed
+        GIT_TAG        v1.3.8 # adjust tag/branch/commit as needed
     )
     FetchContent_MakeAvailable(parallel-hashmap)
 

doc/new_release.md

@@ -1,7 +1,7 @@
 - update version in phmap_config.h
 - update version in comment on top of CMakeLists.txt
-- create the new release on github (tag `1.3.8` - use semantic versioning)
-- download the tar.gz from github, and use `sha256sum parallel-hashmap-1.3.8.tar.gz` on linux to get the sha256
+- create the new release on github (tag `v1.3.8` - use semantic versioning)
+- download the tar.gz from github, and use `sha256sum parallel-hashmap-v1.3.8.tar.gz` on linux to get the sha256
 
 ## conan