Fix deprecated imports from jinja2

For the escape change see [1].

[1]: https://github.com/pallets/jinja/issues/1626

pastesrht/blueprints/public.py

@@ -2,7 +2,7 @@ import pygments
 from flask import Blueprint, render_template, request, redirect, Response
 from flask import url_for, abort
 from hashlib import sha1
-from jinja2 import Markup
+from markupsafe import Markup
 from pastesrht.access import get_paste_or_abort, get_user_or_abort, has_access, paste_add_file, paste_drop, DbLock, UserAccess
 from pastesrht.types import Paste, PasteFile, PasteVisibility, Blob
 from pastesrht.search import apply_search

pastesrht/filters.py

@@ -1,5 +1,5 @@
 import yaml
-from jinja2 import escape
+from markupsafe import escape
 from srht.markdown import markdown
 
 def extract_frontmatter(content):