Update to 0.9721
Add missing DEPENDS

Upstream changes:
0.9721 2021-04-18
- fix BitMatrix and AdjacencyMatrix problems - thanks @dod38fr for report

0.9720 2021-03-25
- better fix - no mutate inputs

0.9719 2021-03-25
- fix all_paths infinite loop on cycle - thanks @tobez for report

0.9718 2021-03-13
- remove doc of deleted average_degree method - thanks @lindleyw for report

0.9717 2021-01-27
- bulk APIs for UnionFind
- add unionfind config option for util/grand.pl (benchmark-ish script)
- GRAPH_ALLOW_RECURSION env var to turn off recursion protection
- "Light" edge-map now uses bit-vectors -> smaller storage
- directed hypergraphs
- fix same_biconnected_components logic when given >2 vertices

0.9716 2021-01-01
- use Set::Object
- {neighbours,successors,predecessors,reachable}_by_radius

0.9715 2020-12-31
- fix AdjacencyMap::Light attributes so delete when path deleted
- fix as_hashes undirected edges: now both directions
- subgraph_by_radius take multiple vertices

0.9714 2020-12-25
- remove "omni*" - hypergraphs are simply directed or undirected
- as_hashes works with undirected hypergraphs
- add_edge with != 2 vertices only for undirected hypergraph
- any_edge
- delete_*_attributes_by_id (and deleting last attribute) now don't destroy that entity
- AdjacencyMap::Light can have attributes, so no slowdown if use (eg APSP)

0.9713 2020-12-19
- fix edges_at on self-edges in scalar context
- fix refvertexed_stringified predicate
- remove "hypervertices": a collection of n vertices is a hyperedge
- AdjacencyMap.get_paths_by_ids
- transitive_closure et al no longer re-bless objects to Graph
- AdjacencyMap.get_ids_by_paths
- no more uniqedged configurability
- BitMatrix transpose option
- Transitive closure records path successor, not predecessor. Method name and docs updated.

0.9712 2020-12-05
- bug-fix: set_edge_attribute_by_id add_edge_by_id if not exist
- connected_component_by_index behaves same with/without unionfind
- AdjacencyMatrix handle multiedged
- reduce redundant sorting for _UNORD, fix AdjacencyMap::Vertex with ID 0
- AdjacencyMap.stringify
- allow constructor args to override "prototype" object
- fix docs for TransitiveClosure to correctly say path_vertices default true
- AdjacencyMatrix now always creates adjacency matrix (clue in name)
- remove compat02 features
- drop untested scalar-context Traversal.postorder mutation behaviour
- much more lazy-loading of modules
- set_vertex_attribute_by_id now works on hypervertexed
- internal AdjacencyMap uses array not hash for mapping index to path
- successors/predecessors/rename_path work right with multivertex
- AdjacencyMap array -> stable vertices ordering, TCM performance benefit
- TransitiveClosure etc handle multiedged
- all_paths ignore self-loops

0.9711 2020-11-27
- ingest handle multivertexed, multiedged right

0.9710 2020-11-27
- all_paths method
- as_hashes handle multivertexed, multiedged right

0.9709 2020-11-22
- add path_count option to TransitiveClosure
- get_{edge,vertex}_attributes undef if no such entity, in list context
- as_hashes method
- ingest method

0.9708 2020-11-06
- update metadata for Test::More version dep
- stringify hypervertices right
- add rename_vertex, rename_vertices

0.9707 2020-10-31
- can't use Safe, ergo Storable, on 5.8

0.9706 2020-10-20
- metadata list test-deps as not runtime

0.9705 2020-10-20
- document clustering_coefficient return empty list on no vertices - RT#114094
- apply lazy-load patch from Stephen Loyd - RT#123236
- depend on Heap 0.80 instead of local fork. Heap::Elem is really an interface not superclass.
- fix uninitialised value warning in SP_Dijkstra - RT#118539
- fix complement losing vertices on unconnected graphs - RT#115366
- fix average_path_length when two vertices given - RT#120611
- switch to GitHub issues rather than RT
- fix all_successors with non-truthy names - fix #5
- add Graph::Matrix->stringify to help debug
- fix APSP_Floyd_Warshall logic error when subpaths totalled 0 - fix #3
- typo fix - thanks @jkeenan (#6)
- Added "use strict; use warnings;", etc - thanks @manwar (closes #2)

(wen)